]> Cypherpunks repositories - gostls13.git/commitdiff
final AES: CMAC authentication and EAX authenticated encryption
authorRuss Cox <rsc@golang.org>
Tue, 19 May 2009 22:41:37 +0000 (15:41 -0700)
committerRuss Cox <rsc@golang.org>
Tue, 19 May 2009 22:41:37 +0000 (15:41 -0700)
R=r
DELTA=791  (779 added, 0 deleted, 12 changed)
OCL=29045
CL=29058

src/lib/crypto/block/cfb.go
src/lib/crypto/block/cipher.go
src/lib/crypto/block/cmac.go [new file with mode: 0644]
src/lib/crypto/block/cmac_aes_test.go [new file with mode: 0644]
src/lib/crypto/block/ctr.go
src/lib/crypto/block/eax.go [new file with mode: 0644]
src/lib/crypto/block/eax_aes_test.go [new file with mode: 0644]
src/lib/crypto/block/ofb.go
src/lib/crypto/block/xor.go
src/lib/crypto/block/xor_test.go

index 827a55ee1c4411fc0280810fbadea7763683c03f..5c4c09a1b1f4df3949f3a7b9ed806aac72b79e92 100644 (file)
@@ -27,7 +27,7 @@ type cfbCipher struct {
 
 func newCFB(c Cipher, s int, iv []byte) *cfbCipher {
        if s == 0 || s % 8 != 0 {
-               panicln("invalid CFB mode", s);
+               panicln("crypto/block: invalid CFB mode", s);
        }
        b := c.BlockSize();
        x := new(cfbCipher);
index 8bff1b87820e8769df8ea0b1ba7db87bb00ec534..7ea035db9a6203621eea429701fb989fc4c7a1a6 100644 (file)
@@ -8,6 +8,8 @@
 // and NIST Special Publication 800-38A.
 package block
 
+import "io";
+
 // A Cipher represents an implementation of block cipher
 // using a given key.  It provides the capability to encrypt
 // or decrypt individual blocks.  The mode implementations
@@ -25,6 +27,20 @@ type Cipher interface {
        Decrypt(src, dst []byte);
 }
 
+// TODO(rsc): Digest belongs elsewhere.
+
+// A Digest is an implementation of a message digest algorithm.
+// Write data to it and then call Sum to retreive the digest.
+// Calling Reset resets the internal state, as though no data has
+// been written.
+type Digest interface {
+       io.Writer;
+       Sum() []byte;
+       Reset();
+}
+
+
+
 // Utility routines
 
 func shift1(src, dst []byte) byte {
diff --git a/src/lib/crypto/block/cmac.go b/src/lib/crypto/block/cmac.go
new file mode 100644 (file)
index 0000000..40697ca
--- /dev/null
@@ -0,0 +1,105 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// CMAC message authentication code, defined in
+// NIST Special Publication SP 800-38B.
+
+package block
+
+import (
+       "crypto/block";
+       "io";
+       "os";
+)
+
+const (
+       // minimal irreducible polynomial of degree b
+       r64 = 0x1b;
+       r128 = 0x87;
+)
+
+type cmac struct {
+       k1, k2, ci, digest []byte;
+       p int;  // position in ci
+       c Cipher;
+}
+
+// TODO(rsc): Should this return an error instead of panic?
+
+// NewCMAC returns a new instance of a CMAC message authentication code
+// digest using the given Cipher.
+func NewCMAC(c Cipher) Digest {
+       var r byte;
+       n := c.BlockSize();
+       switch n {
+       case 64/8:
+               r = r64;
+       case 128/8:
+               r = r128;
+       default:
+               panic("crypto/block: NewCMAC: invalid cipher block size", n);
+       }
+
+       d := new(cmac);
+       d.c = c;
+       d.k1 = make([]byte, n);
+       d.k2 = make([]byte, n);
+       d.ci = make([]byte, n);
+       d.digest = make([]byte, n);
+
+       // Subkey generation, p. 7
+       c.Encrypt(d.k1, d.k1);
+       if shift1(d.k1, d.k1) != 0 {
+               d.k1[n-1] ^= r;
+       }
+       if shift1(d.k1, d.k2) != 0 {
+               d.k2[n-1] ^= r;
+       }
+
+       return d;
+}
+
+// Reset clears the digest state, starting a new digest.
+func (d *cmac) Reset() {
+       for i := range d.ci {
+               d.ci[i] = 0;
+       }
+       d.p = 0;
+}
+
+// Write adds the given data to the digest state.
+func (d *cmac) Write(p []byte) (n int, err os.Error) {
+       // Xor input into ci.
+       for i, c := range p {
+               // If ci is full, encrypt and start over.
+               if d.p >= len(d.ci) {
+                       d.c.Encrypt(d.ci, d.ci);
+                       d.p = 0;
+               }
+               d.ci[d.p] ^= c;
+               d.p++;
+       }
+       return len(p), nil;
+}
+
+// Sum returns the CMAC digest, one cipher block in length,
+// of the data written with Write.
+func (d *cmac) Sum() []byte {
+       // Finish last block, mix in key, encrypt.
+       // Don't edit ci, in case caller wants
+       // to keep digesting after call to Sum.
+       k := d.k1;
+       if d.p < len(d.digest) {
+               k = d.k2;
+       }
+       for i := 0; i < len(d.ci); i++ {
+               d.digest[i] = d.ci[i] ^ k[i];
+       }
+       if d.p < len(d.digest) {
+               d.digest[d.p] ^= 0x80;
+       }
+       d.c.Encrypt(d.digest, d.digest);
+       return d.digest;
+}
+
diff --git a/src/lib/crypto/block/cmac_aes_test.go b/src/lib/crypto/block/cmac_aes_test.go
new file mode 100644 (file)
index 0000000..9284ac4
--- /dev/null
@@ -0,0 +1,165 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// CMAC test vectors.  See NIST SP 800-38B, Appendix D.
+
+package block
+
+// gobuild: $GC ecb_aes_test.go
+
+import (
+       "crypto/aes";
+       "crypto/block";
+       "testing";
+
+       "./ecb_aes_test";
+)
+
+type cmacAESTest struct {
+       key []byte;
+       in []byte;
+       digest []byte;
+}
+
+var cmacAESTests = []cmacAESTest {
+       cmacAESTest {
+               commonKey128,
+               nil,
+               []byte {
+                       0xbb, 0x1d, 0x69, 0x29, 0xe9, 0x59, 0x37, 0x28, 0x7f, 0xa3, 0x7d, 0x12, 0x9b, 0x75, 0x67, 0x46,
+               }
+       },
+       cmacAESTest {
+               commonKey128,
+               []byte {
+                       0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+               },
+               []byte {
+                       0x07, 0x0a, 0x16, 0xb4, 0x6b, 0x4d, 0x41, 0x44, 0xf7, 0x9b, 0xdd, 0x9d, 0xd0, 0x4a, 0x28, 0x7c,
+               }
+       },
+       cmacAESTest {
+               commonKey128,
+               []byte {
+                       0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+                       0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
+                       0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11,
+               },
+               []byte {
+                       0xdf, 0xa6, 0x67, 0x47, 0xde, 0x9a, 0xe6, 0x30, 0x30, 0xca, 0x32, 0x61, 0x14, 0x97, 0xc8, 0x27,
+               }
+       },
+       cmacAESTest {
+               commonKey128,
+               []byte {
+                       0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+                       0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
+                       0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11, 0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,
+                       0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17, 0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10,
+               },
+               []byte {
+                       0x51, 0xf0, 0xbe, 0xbf, 0x7e, 0x3b, 0x9d, 0x92, 0xfc, 0x49, 0x74, 0x17, 0x79, 0x36, 0x3c, 0xfe,
+               }
+       },
+       cmacAESTest {
+               commonKey192,
+               nil,
+               []byte {
+                       0xd1, 0x7d, 0xdf, 0x46, 0xad, 0xaa, 0xcd, 0xe5, 0x31, 0xca, 0xc4, 0x83, 0xde, 0x7a, 0x93, 0x67,
+               }
+       },
+       cmacAESTest {
+               commonKey192,
+               []byte {
+                       0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+               },
+               []byte {
+                       0x9e, 0x99, 0xa7, 0xbf, 0x31, 0xe7, 0x10, 0x90, 0x06, 0x62, 0xf6, 0x5e, 0x61, 0x7c, 0x51, 0x84,
+               }
+       },
+       cmacAESTest {
+               commonKey192,
+               []byte {
+                       0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+                       0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
+                       0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11,
+               },
+               []byte {
+                       0x8a, 0x1d, 0xe5, 0xbe, 0x2e, 0xb3, 0x1a, 0xad, 0x08, 0x9a, 0x82, 0xe6, 0xee, 0x90, 0x8b, 0x0e,
+               }
+       },
+       cmacAESTest {
+               commonKey192,
+               []byte {
+                       0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+                       0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
+                       0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11, 0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,
+                       0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17, 0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10,
+               },
+               []byte {
+                       0xa1, 0xd5, 0xdf, 0x0e, 0xed, 0x79, 0x0f, 0x79, 0x4d, 0x77, 0x58, 0x96, 0x59, 0xf3, 0x9a, 0x11,
+               }
+       },
+       cmacAESTest {
+               commonKey256,
+               nil,
+               []byte {
+                       0x02, 0x89, 0x62, 0xf6, 0x1b, 0x7b, 0xf8, 0x9e, 0xfc, 0x6b, 0x55, 0x1f, 0x46, 0x67, 0xd9, 0x83,
+               }
+       },
+       cmacAESTest {
+               commonKey256,
+               []byte {
+                       0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+               },
+               []byte {
+                       0x28, 0xa7, 0x02, 0x3f, 0x45, 0x2e, 0x8f, 0x82, 0xbd, 0x4b, 0xf2, 0x8d, 0x8c, 0x37, 0xc3, 0x5c,
+               }
+       },
+       cmacAESTest {
+               commonKey256,
+               []byte {
+                       0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+                       0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
+                       0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11,
+               },
+               []byte {
+                       0xaa, 0xf3, 0xd8, 0xf1, 0xde, 0x56, 0x40, 0xc2, 0x32, 0xf5, 0xb1, 0x69, 0xb9, 0xc9, 0x11, 0xe6,
+               }
+       },
+       cmacAESTest {
+               commonKey256,
+               []byte {
+                       0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+                       0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
+                       0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11, 0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,
+                       0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17, 0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10,
+               },
+               []byte {
+                       0xe1, 0x99, 0x21, 0x90, 0x54, 0x9f, 0x6e, 0xd5, 0x69, 0x6a, 0x2c, 0x05, 0x6c, 0x31, 0x54, 0x10,
+               }
+       }
+}
+
+func TestCMAC_AES(t *testing.T) {
+       for i, tt := range cmacAESTests {
+               c, err := aes.NewCipher(tt.key);
+               if err != nil {
+                       t.Errorf("test %d: NewCipher: %s", i, err);
+                       continue;
+               }
+               d := NewCMAC(c);
+               n, err := d.Write(tt.in);
+               if err != nil || n != len(tt.in) {
+                       t.Errorf("test %d: Write %d: %d, %s", i, len(tt.in), n, err);
+                       continue;
+               }
+               sum := d.Sum();
+               if !same(sum, tt.digest) {
+                       x := d.(*cmac);
+                       t.Errorf("test %d: digest mismatch\n\twant %x\n\thave %x\n\tk1 %x\n\tk2 %x", i, tt.digest, sum, x.k1, x.k2);
+                       continue;
+               }
+       }
+}
index 98fd1939229f3554db5d4a189f1944ccabc8844a..eecb615ad10a9b2cd479c058ad52b2a2aede7851 100644 (file)
@@ -53,7 +53,7 @@ func (x *ctrStream) Next() []byte {
 // a CTR reader applied to an encrypted stream produces a decrypted
 // stream and vice versa.
 func NewCTRReader(c Cipher, iv []byte, r io.Reader) io.Reader {
-       return NewXorReader(newCTRStream(c, iv), r);
+       return newXorReader(newCTRStream(c, iv), r);
 }
 
 // NewCTRWriter returns a writer that encrypts (or decrypts) data using c
@@ -64,6 +64,6 @@ func NewCTRReader(c Cipher, iv []byte, r io.Reader) io.Reader {
 // a CTR writer applied to an decrypted stream produces an encrypted
 // stream and vice versa.
 func NewCTRWriter(c Cipher, iv []byte, w io.Writer) io.Writer {
-       return NewXorWriter(newCTRStream(c, iv), w);
+       return newXorWriter(newCTRStream(c, iv), w);
 }
 
diff --git a/src/lib/crypto/block/eax.go b/src/lib/crypto/block/eax.go
new file mode 100644 (file)
index 0000000..7e1d747
--- /dev/null
@@ -0,0 +1,254 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// EAX mode, not a NIST standard (yet).
+// EAX provides encryption and authentication.
+// EAX targets the same uses as NIST's CCM mode,
+// but EAX adds the ability to run in streaming mode.
+
+// See
+// http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/eax/eax-spec.pdf
+// http://www.cs.ucdavis.edu/~rogaway/papers/eax.pdf
+// What those papers call OMAC is now called CMAC.
+
+package block
+
+import (
+       "crypto/block";
+       "fmt";
+       "io";
+       "os";
+)
+
+// An EAXTagError is returned when the message has failed to authenticate,
+// because the tag at the end of the message stream (Read) does not match
+// the tag computed from the message itself (Computed).
+type EAXTagError struct {
+       Read []byte;
+       Computed []byte;
+}
+
+func (e *EAXTagError) String() string {
+       return fmt.Sprintf("crypto/block: EAX tag mismatch: read %x but computed %x", e.Read, e.Computed);
+}
+
+func setupEAX(c Cipher, iv, hdr []byte, tagBytes int) (ctrIV, tag []byte, cmac Digest) {
+       n := len(iv);
+       if n != c.BlockSize() {
+               panicln("crypto/block: EAX: iv length", n, "!=", c.BlockSize());
+       }
+       buf := make([]byte, n); // zeroed
+
+       // tag = CMAC(0 + iv) ^ CMAC(1 + hdr) ^ CMAC(2 + data)
+       cmac = NewCMAC(c);
+       cmac.Write(buf);        // 0
+       cmac.Write(iv);
+       sum := cmac.Sum();
+       ctrIV = copy(sum);
+       tag = copy(sum[0:tagBytes]);
+
+       cmac.Reset();
+       buf[n-1] = 1;
+       cmac.Write(buf);        // 1
+       cmac.Write(hdr);
+       sum = cmac.Sum();
+       for i := 0; i < tagBytes; i++ {
+               tag[i] ^= sum[i];
+       }
+
+       cmac.Reset();
+       buf[n-1] = 2;           // 2
+       cmac.Write(buf);
+
+       return;
+}
+
+func finishEAX(tag []byte, cmac Digest) {
+       // Finish CMAC #2 and xor into tag.
+       sum := cmac.Sum();
+       for i := range tag {
+               tag[i] ^= sum[i];
+       }
+}
+
+// Writer adapter.  Tees writes into both w and cmac.
+// Knows that cmac never returns write errors.
+type cmacWriter struct {
+       w io.Writer;
+       cmac Digest;
+}
+
+func (cw *cmacWriter) Write(p []byte) (n int, err os.Error) {
+       n, err = cw.w.Write(p);
+       cw.cmac.Write(p[0:n]);
+       return;
+}
+
+// An eaxEncrypter implements the EAX encryption mode.
+type eaxEncrypter struct {
+       ctr io.Writer;  // CTR encrypter
+       cw cmacWriter;  // CTR's output stream
+       tag []byte;
+}
+
+// NewEAXEncrypter creates and returns a new EAX encrypter
+// using the given cipher c, initialization vector iv, associated data hdr,
+// and tag length tagBytes.  The encrypter's Write method encrypts
+// the data it receives and writes that data to w.
+// The encrypter's Close method writes a final authenticating tag to w.
+func NewEAXEncrypter(c Cipher, iv []byte, hdr []byte, tagBytes int, w io.Writer) io.WriteCloser {
+       x := new(eaxEncrypter);
+
+       // Create new CTR instance writing to both
+       // w for encrypted output and cmac for digesting.
+       x.cw.w = w;
+       var ctrIV []byte;
+       ctrIV, x.tag, x.cw.cmac = setupEAX(c, iv, hdr, tagBytes);
+       x.ctr = NewCTRWriter(c, ctrIV, &x.cw);
+       return x;
+}
+
+func (x *eaxEncrypter) Write(p []byte) (n int, err os.Error) {
+       return x.ctr.Write(p);
+}
+
+func (x *eaxEncrypter) Close() os.Error {
+       x.ctr = nil;    // crash if Write is called again
+
+       // Write tag.
+       finishEAX(x.tag, x.cw.cmac);
+       n, err := x.cw.w.Write(x.tag);
+       if n != len(x.tag) && err == nil {
+               err = io.ErrShortWrite;
+       }
+
+       return err;
+}
+
+// Reader adapter.  Returns data read from r but hangs
+// on to the last len(tag) bytes for itself (returns EOF len(tag)
+// bytes early).  Also tees all data returned from Read into
+// the cmac digest.  The "don't return the last t bytes"
+// and the "tee into digest" functionality could be separated,
+// but the latter half is trivial.
+type cmacReader struct {
+       r io.Reader;
+       cmac Digest;
+       tag []byte;
+       tmp []byte;
+}
+
+func (cr *cmacReader) Read(p []byte) (n int, err os.Error) {
+       // TODO(rsc): Maybe fall back to simpler code if
+       // we recognize the underlying r as a ByteBuffer
+       // or ByteReader.  Then we can just take the last piece
+       // off at the start.
+
+       // First, read a tag-sized chunk.
+       // It's probably not the tag (unless there's no data).
+       tag := cr.tag;
+       if len(tag) < cap(tag) {
+               nt := len(tag);
+               nn, err1 := io.FullRead(cr.r, tag[nt:cap(tag)]);
+               tag = tag[0:nt+nn];
+               cr.tag = tag;
+               if err1 != nil {
+                       return 0, err1;
+               }
+       }
+
+       tagBytes := len(tag);
+       if len(p) > 4*tagBytes {
+               // If p is big, try to read directly into p to avoid a copy.
+               n, err = cr.r.Read(p[tagBytes:len(p)]);
+               if n == 0 {
+                       goto out;
+               }
+               // copy old tag into p
+               for i := 0; i < tagBytes; i++ {
+                       p[i] = tag[i];
+               }
+               // copy new tag out of p
+               for i := 0; i < tagBytes; i++ {
+                       tag[i] = p[n+i];
+               }
+               goto out;
+       }
+
+       // Otherwise, read into p and then slide data
+       n, err = cr.r.Read(p);
+       if n == 0 {
+               goto out;
+       }
+
+       // copy tag+p into p+tmp and then swap tmp, tag
+       tmp := cr.tmp;
+       for i := n + tagBytes - 1; i >= 0; i-- {
+               var c byte;
+               if i < tagBytes {
+                       c = tag[i];
+               } else {
+                       c = p[i - tagBytes];
+               }
+               if i < n {
+                       p[i] = c;
+               } else {
+                       tmp[i] = c;
+               }
+       }
+       cr.tmp, cr.tag = tag, tmp;
+
+out:
+       cr.cmac.Write(p[0:n]);
+       return;
+}
+
+type eaxDecrypter struct {
+       ctr io.Reader;
+       cr cmacReader;
+       tag []byte;
+}
+
+// NewEAXDecrypter creates and returns a new EAX decrypter
+// using the given cipher c, initialization vector iv, associated data hdr,
+// and tag length tagBytes.  The encrypter's Read method decrypts and
+// returns data read from r.  At r's EOF, the encrypter checks the final
+// authenticating tag and returns an EAXTagError if the tag is invalid.
+// In that case, the message should be discarded.
+// Note that the data stream returned from Read cannot be
+// assumed to be valid, authenticated data until Read returns
+// 0, nil to signal the end of the data.
+func NewEAXDecrypter(c Cipher, iv []byte, hdr []byte, tagBytes int, r io.Reader) io.Reader {
+       x := new(eaxDecrypter);
+
+       x.cr.r = r;
+       x.cr.tag = make([]byte, 0, tagBytes);
+       x.cr.tmp = make([]byte, 0, tagBytes);
+       var ctrIV []byte;
+       ctrIV, x.tag, x.cr.cmac = setupEAX(c, iv, hdr, tagBytes);
+       x.ctr = NewCTRReader(c, ctrIV, &x.cr);
+       return x;
+}
+
+func (x *eaxDecrypter) checkTag() os.Error {
+       x.ctr = nil;    // crash if Read is called again
+
+       finishEAX(x.tag, x.cr.cmac);
+       if !same(x.tag, x.cr.tag) {
+               e := new(EAXTagError);
+               e.Computed = copy(x.tag);
+               e.Read = copy(x.cr.tag);
+               return e;
+       }
+       return nil;
+}
+
+func (x *eaxDecrypter) Read(p []byte) (n int, err os.Error) {
+       n, err = x.ctr.Read(p);
+       if n == 0 && err == nil {
+               err = x.checkTag();
+       }
+       return n, err;
+}
+
diff --git a/src/lib/crypto/block/eax_aes_test.go b/src/lib/crypto/block/eax_aes_test.go
new file mode 100644 (file)
index 0000000..f0453be
--- /dev/null
@@ -0,0 +1,239 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package block
+
+import (
+       "crypto/aes";
+       "crypto/block";
+       "fmt";
+       "io";
+       "testing";
+)
+
+// Test vectors from http://www.cs.ucdavis.edu/~rogaway/papers/eax.pdf
+
+type eaxAESTest struct {
+       msg []byte;
+       key []byte;
+       nonce []byte;
+       header []byte;
+       cipher []byte;
+}
+
+var eaxAESTests = []eaxAESTest {
+       eaxAESTest {
+               []byte {
+               },
+               []byte {
+                       0x23, 0x39, 0x52, 0xDE, 0xE4, 0xD5, 0xED, 0x5F, 0x9B, 0x9C, 0x6D, 0x6F, 0xF8, 0x0F, 0xF4, 0x78,
+               },
+               []byte {
+                       0x62, 0xEC, 0x67, 0xF9, 0xC3, 0xA4, 0xA4, 0x07, 0xFC, 0xB2, 0xA8, 0xC4, 0x90, 0x31, 0xA8, 0xB3,
+               },
+               []byte {
+                       0x6B, 0xFB, 0x91, 0x4F, 0xD0, 0x7E, 0xAE, 0x6B,
+               },
+               []byte {
+                       0xE0, 0x37, 0x83, 0x0E, 0x83, 0x89, 0xF2, 0x7B, 0x02, 0x5A, 0x2D, 0x65, 0x27, 0xE7, 0x9D, 0x01,
+               },
+       },
+       eaxAESTest {
+               []byte {
+                       0xF7, 0xFB,
+               },
+               []byte {
+                       0x91, 0x94, 0x5D, 0x3F, 0x4D, 0xCB, 0xEE, 0x0B, 0xF4, 0x5E, 0xF5, 0x22, 0x55, 0xF0, 0x95, 0xA4,
+               },
+               []byte {
+                       0xBE, 0xCA, 0xF0, 0x43, 0xB0, 0xA2, 0x3D, 0x84, 0x31, 0x94, 0xBA, 0x97, 0x2C, 0x66, 0xDE, 0xBD,
+               },
+               []byte {
+                       0xFA, 0x3B, 0xFD, 0x48, 0x06, 0xEB, 0x53, 0xFA,
+               },
+               []byte {
+                       0x19, 0xDD, 0x5C, 0x4C, 0x93, 0x31, 0x04, 0x9D, 0x0B, 0xDA, 0xB0, 0x27, 0x74, 0x08, 0xF6, 0x79, 0x67, 0xE5,
+               },
+       },
+       eaxAESTest {
+               []byte {
+                       0x1A, 0x47, 0xCB, 0x49, 0x33,
+               },
+               []byte {
+                       0x01, 0xF7, 0x4A, 0xD6, 0x40, 0x77, 0xF2, 0xE7, 0x04, 0xC0, 0xF6, 0x0A, 0xDA, 0x3D, 0xD5, 0x23,
+               },
+               []byte {
+                       0x70, 0xC3, 0xDB, 0x4F, 0x0D, 0x26, 0x36, 0x84, 0x00, 0xA1, 0x0E, 0xD0, 0x5D, 0x2B, 0xFF, 0x5E,
+               },
+               []byte {
+                       0x23, 0x4A, 0x34, 0x63, 0xC1, 0x26, 0x4A, 0xC6,
+               },
+               []byte {
+                       0xD8, 0x51, 0xD5, 0xBA, 0xE0, 0x3A, 0x59, 0xF2, 0x38, 0xA2, 0x3E, 0x39, 0x19, 0x9D, 0xC9, 0x26, 0x66, 0x26, 0xC4, 0x0F, 0x80,
+               },
+       },
+       eaxAESTest {
+               []byte {
+                       0x48, 0x1C, 0x9E, 0x39, 0xB1,
+               },
+               []byte {
+                       0xD0, 0x7C, 0xF6, 0xCB, 0xB7, 0xF3, 0x13, 0xBD, 0xDE, 0x66, 0xB7, 0x27, 0xAF, 0xD3, 0xC5, 0xE8,
+               },
+               []byte {
+                       0x84, 0x08, 0xDF, 0xFF, 0x3C, 0x1A, 0x2B, 0x12, 0x92, 0xDC, 0x19, 0x9E, 0x46, 0xB7, 0xD6, 0x17,
+               },
+               []byte {
+                       0x33, 0xCC, 0xE2, 0xEA, 0xBF, 0xF5, 0xA7, 0x9D,
+               },
+               []byte {
+                       0x63, 0x2A, 0x9D, 0x13, 0x1A, 0xD4, 0xC1, 0x68, 0xA4, 0x22, 0x5D, 0x8E, 0x1F, 0xF7, 0x55, 0x93, 0x99, 0x74, 0xA7, 0xBE, 0xDE,
+               },
+       },
+       eaxAESTest {
+               []byte {
+                       0x40, 0xD0, 0xC0, 0x7D, 0xA5, 0xE4,
+               },
+               []byte {
+                       0x35, 0xB6, 0xD0, 0x58, 0x00, 0x05, 0xBB, 0xC1, 0x2B, 0x05, 0x87, 0x12, 0x45, 0x57, 0xD2, 0xC2,
+               },
+               []byte {
+                       0xFD, 0xB6, 0xB0, 0x66, 0x76, 0xEE, 0xDC, 0x5C, 0x61, 0xD7, 0x42, 0x76, 0xE1, 0xF8, 0xE8, 0x16,
+               },
+               []byte {
+                       0xAE, 0xB9, 0x6E, 0xAE, 0xBE, 0x29, 0x70, 0xE9,
+               },
+               []byte {
+                       0x07, 0x1D, 0xFE, 0x16, 0xC6, 0x75, 0xCB, 0x06, 0x77, 0xE5, 0x36, 0xF7, 0x3A, 0xFE, 0x6A, 0x14, 0xB7, 0x4E, 0xE4, 0x98, 0x44, 0xDD,
+               },
+       },
+       eaxAESTest {
+               []byte {
+                       0x4D, 0xE3, 0xB3, 0x5C, 0x3F, 0xC0, 0x39, 0x24, 0x5B, 0xD1, 0xFB, 0x7D,
+               },
+               []byte {
+                       0xBD, 0x8E, 0x6E, 0x11, 0x47, 0x5E, 0x60, 0xB2, 0x68, 0x78, 0x4C, 0x38, 0xC6, 0x2F, 0xEB, 0x22,
+               },
+               []byte {
+                       0x6E, 0xAC, 0x5C, 0x93, 0x07, 0x2D, 0x8E, 0x85, 0x13, 0xF7, 0x50, 0x93, 0x5E, 0x46, 0xDA, 0x1B,
+               },
+               []byte {
+                       0xD4, 0x48, 0x2D, 0x1C, 0xA7, 0x8D, 0xCE, 0x0F,
+               },
+               []byte {
+                       0x83, 0x5B, 0xB4, 0xF1, 0x5D, 0x74, 0x3E, 0x35, 0x0E, 0x72, 0x84, 0x14, 0xAB, 0xB8, 0x64, 0x4F, 0xD6, 0xCC, 0xB8, 0x69, 0x47, 0xC5, 0xE1, 0x05, 0x90, 0x21, 0x0A, 0x4F,
+               },
+       },
+       eaxAESTest {
+               []byte {
+                       0x8B, 0x0A, 0x79, 0x30, 0x6C, 0x9C, 0xE7, 0xED, 0x99, 0xDA, 0xE4, 0xF8, 0x7F, 0x8D, 0xD6, 0x16, 0x36,
+               },
+               []byte {
+                       0x7C, 0x77, 0xD6, 0xE8, 0x13, 0xBE, 0xD5, 0xAC, 0x98, 0xBA, 0xA4, 0x17, 0x47, 0x7A, 0x2E, 0x7D,
+               },
+               []byte {
+                       0x1A, 0x8C, 0x98, 0xDC, 0xD7, 0x3D, 0x38, 0x39, 0x3B, 0x2B, 0xF1, 0x56, 0x9D, 0xEE, 0xFC, 0x19,
+               },
+               []byte {
+                       0x65, 0xD2, 0x01, 0x79, 0x90, 0xD6, 0x25, 0x28,
+               },
+               []byte {
+                       0x02, 0x08, 0x3E, 0x39, 0x79, 0xDA, 0x01, 0x48, 0x12, 0xF5, 0x9F, 0x11, 0xD5, 0x26, 0x30, 0xDA, 0x30, 0x13, 0x73, 0x27, 0xD1, 0x06, 0x49, 0xB0, 0xAA, 0x6E, 0x1C, 0x18, 0x1D, 0xB6, 0x17, 0xD7, 0xF2,
+               },
+       },
+       eaxAESTest {
+               []byte {
+                       0x1B, 0xDA, 0x12, 0x2B, 0xCE, 0x8A, 0x8D, 0xBA, 0xF1, 0x87, 0x7D, 0x96, 0x2B, 0x85, 0x92, 0xDD, 0x2D, 0x56,
+               },
+               []byte {
+                       0x5F, 0xFF, 0x20, 0xCA, 0xFA, 0xB1, 0x19, 0xCA, 0x2F, 0xC7, 0x35, 0x49, 0xE2, 0x0F, 0x5B, 0x0D,
+               },
+               []byte {
+                       0xDD, 0xE5, 0x9B, 0x97, 0xD7, 0x22, 0x15, 0x6D, 0x4D, 0x9A, 0xFF, 0x2B, 0xC7, 0x55, 0x98, 0x26,
+               },
+               []byte {
+                       0x54, 0xB9, 0xF0, 0x4E, 0x6A, 0x09, 0x18, 0x9A,
+               },
+               []byte {
+                       0x2E, 0xC4, 0x7B, 0x2C, 0x49, 0x54, 0xA4, 0x89, 0xAF, 0xC7, 0xBA, 0x48, 0x97, 0xED, 0xCD, 0xAE, 0x8C, 0xC3, 0x3B, 0x60, 0x45, 0x05, 0x99, 0xBD, 0x02, 0xC9, 0x63, 0x82, 0x90, 0x2A, 0xEF, 0x7F, 0x83, 0x2A,
+               },
+       },
+       eaxAESTest {
+               []byte {
+                       0x6C, 0xF3, 0x67, 0x20, 0x87, 0x2B, 0x85, 0x13, 0xF6, 0xEA, 0xB1, 0xA8, 0xA4, 0x44, 0x38, 0xD5, 0xEF, 0x11,
+               },
+               []byte {
+                       0xA4, 0xA4, 0x78, 0x2B, 0xCF, 0xFD, 0x3E, 0xC5, 0xE7, 0xEF, 0x6D, 0x8C, 0x34, 0xA5, 0x61, 0x23,
+               },
+               []byte {
+                       0xB7, 0x81, 0xFC, 0xF2, 0xF7, 0x5F, 0xA5, 0xA8, 0xDE, 0x97, 0xA9, 0xCA, 0x48, 0xE5, 0x22, 0xEC,
+               },
+               []byte {
+                       0x89, 0x9A, 0x17, 0x58, 0x97, 0x56, 0x1D, 0x7E,
+               },
+               []byte {
+                       0x0D, 0xE1, 0x8F, 0xD0, 0xFD, 0xD9, 0x1E, 0x7A, 0xF1, 0x9F, 0x1D, 0x8E, 0xE8, 0x73, 0x39, 0x38, 0xB1, 0xE8, 0xE7, 0xF6, 0xD2, 0x23, 0x16, 0x18, 0x10, 0x2F, 0xDB, 0x7F, 0xE5, 0x5F, 0xF1, 0x99, 0x17, 0x00,
+               },
+       },
+       eaxAESTest {
+               []byte {
+                       0xCA, 0x40, 0xD7, 0x44, 0x6E, 0x54, 0x5F, 0xFA, 0xED, 0x3B, 0xD1, 0x2A, 0x74, 0x0A, 0x65, 0x9F, 0xFB, 0xBB, 0x3C, 0xEA, 0xB7,
+               },
+               []byte {
+                       0x83, 0x95, 0xFC, 0xF1, 0xE9, 0x5B, 0xEB, 0xD6, 0x97, 0xBD, 0x01, 0x0B, 0xC7, 0x66, 0xAA, 0xC3,
+               },
+               []byte {
+                       0x22, 0xE7, 0xAD, 0xD9, 0x3C, 0xFC, 0x63, 0x93, 0xC5, 0x7E, 0xC0, 0xB3, 0xC1, 0x7D, 0x6B, 0x44,
+               },
+               []byte {
+                       0x12, 0x67, 0x35, 0xFC, 0xC3, 0x20, 0xD2, 0x5A,
+               },
+               []byte {
+                       0xCB, 0x89, 0x20, 0xF8, 0x7A, 0x6C, 0x75, 0xCF, 0xF3, 0x96, 0x27, 0xB5, 0x6E, 0x3E, 0xD1, 0x97, 0xC5, 0x52, 0xD2, 0x95, 0xA7, 0xCF, 0xC4, 0x6A, 0xFC, 0x25, 0x3B, 0x46, 0x52, 0xB1, 0xAF, 0x37, 0x95, 0xB1, 0x24, 0xAB, 0x6E,
+               },
+       },
+}
+
+func TestEAXEncrypt_AES(t *testing.T) {
+       b := new(io.ByteBuffer);
+       for i, tt := range eaxAESTests {
+               test := fmt.Sprintf("test %d", i);
+               c, err := aes.NewCipher(tt.key);
+               if err != nil {
+                       t.Fatalf("%s: NewCipher(%d bytes) = %s", test, len(tt.key), err);
+               }
+               b.Reset();
+               enc := NewEAXEncrypter(c, tt.nonce, tt.header, 16, b);
+               n, err := io.Copy(io.NewByteReader(tt.msg), enc);
+               if n != int64(len(tt.msg)) || err != nil {
+                       t.Fatalf("%s: io.Copy into encrypter: %d, %s", test, n, err);
+               }
+               err = enc.Close();
+               if err != nil {
+                       t.Fatalf("%s: enc.Close: %s", test, err);
+               }
+               if d := b.Data(); !same(d, tt.cipher) {
+                       t.Fatalf("%s: got %x want %x", test, d, tt.cipher);
+               }
+       }
+}
+
+func TestEAXDecrypt_AES(t *testing.T) {
+       b := new(io.ByteBuffer);
+       for i, tt := range eaxAESTests {
+               test := fmt.Sprintf("test %d", i);
+               c, err := aes.NewCipher(tt.key);
+               if err != nil {
+                       t.Fatalf("%s: NewCipher(%d bytes) = %s", test, len(tt.key), err);
+               }
+               b.Reset();
+               dec := NewEAXDecrypter(c, tt.nonce, tt.header, 16, io.NewByteReader(tt.cipher));
+               n, err := io.Copy(dec, b);
+               if n != int64(len(tt.msg)) || err != nil {
+                       t.Fatalf("%s: io.Copy into decrypter: %d, %s", test, n, err);
+               }
+               if d := b.Data(); !same(d, tt.msg) {
+                       t.Fatalf("%s: got %x want %x", test, d, tt.msg);
+               }
+       }
+}
index 10f9a77371e67b23afb688fad6c670deaf1f460e..084274a084fad1c5e7dedd2d4dd08d10eab4c075 100644 (file)
@@ -45,7 +45,7 @@ func (x *ofbStream) Next() []byte {
 // an OFB reader applied to an encrypted stream produces a decrypted
 // stream and vice versa.
 func NewOFBReader(c Cipher, iv []byte, r io.Reader) io.Reader {
-       return NewXorReader(newOFBStream(c, iv), r);
+       return newXorReader(newOFBStream(c, iv), r);
 }
 
 // NewOFBWriter returns a writer that encrypts (or decrypts) data using c
@@ -56,6 +56,6 @@ func NewOFBReader(c Cipher, iv []byte, r io.Reader) io.Reader {
 // an OFB writer applied to an decrypted stream produces an encrypted
 // stream and vice versa.
 func NewOFBWriter(c Cipher, iv []byte, w io.Writer) io.Writer {
-       return NewXorWriter(newOFBStream(c, iv), w);
+       return newXorWriter(newOFBStream(c, iv), w);
 }
 
index 35c18138442637e0bcbb82ebb9f4e1eb1cbb6c7f..63229dbb4039b6b605d25b668170f2c8f785fcb9 100644 (file)
@@ -12,17 +12,21 @@ import (
        "os";
 )
 
-type DataStream interface {
+// A dataStream is an interface to an unending stream of data,
+// used by XorReader and XorWriter to model a pseudo-random generator.
+// Calls to Next() return sequential blocks of data from the stream.
+// Each call must return at least one byte: there is no EOF.
+type dataStream interface {
        Next() []byte
 }
 
 type xorReader struct {
        r io.Reader;
-       rand DataStream;        // pseudo-random
+       rand dataStream;        // pseudo-random
        buf []byte;             // data available from last call to rand
 }
 
-func NewXorReader(rand DataStream, r io.Reader) io.Reader {
+func newXorReader(rand dataStream, r io.Reader) io.Reader {
        x := new(xorReader);
        x.r = r;
        x.rand = rand;
@@ -49,13 +53,13 @@ func (x *xorReader) Read(p []byte) (n int, err os.Error) {
 
 type xorWriter struct {
        w io.Writer;
-       rand DataStream;        // pseudo-random
+       rand dataStream;        // pseudo-random
        buf []byte;     // last buffer returned by rand
        extra []byte;   // extra random data (use before buf)
        work []byte;    // work space
 }
 
-func NewXorWriter(rand DataStream, w io.Writer) io.Writer {
+func newXorWriter(rand dataStream, w io.Writer) io.Writer {
        x := new(xorWriter);
        x.w = w;
        x.rand = rand;
index a2166f884cbeef21d22302fc5049315ef29f7840..6e6d1a3ce97c212c167c97ee904455c46bfe8a81 100644 (file)
@@ -55,7 +55,7 @@ func testXorWriter(t *testing.T, maxio int) {
                        b.Reset();
                        r := io.NewByteReader(&plain);
                        s := newIncStream(block);
-                       w := NewXorWriter(s, b);
+                       w := newXorWriter(s, b);
 
                        // copy plain into w in increasingly large chunks: 1, 1, 2, 4, 8, ...
                        // if frag != 0, move the 1 to the end to cause fragmentation.
@@ -123,7 +123,7 @@ func testXorReader(t *testing.T, maxio int) {
                                test := fmt.Sprintf("block=%d mode=%d frag=%d maxio=%d", block, mode, frag, maxio);
                                s := newIncStream(block);
                                b.Reset();
-                               r := NewXorReader(s, readers[mode](io.NewByteReader(crypt[0:maxio])));
+                               r := newXorReader(s, readers[mode](io.NewByteReader(crypt[0:maxio])));
 
                                // read from crypt in increasingly large chunks: 1, 1, 2, 4, 8, ...
                                // if frag == 1, move the 1 to the end to cause fragmentation.