crypto: add BLAKE2b and BLAKE2s hash constants

Fixes golang/go#19060
Change-Id: I1844edc3dcccc8d83a11d1145b60b2b92f2658ca
Reviewed-on: https://go-review.googlesource.com/36876Reviewed-by: Adam Langley <agl@golang.org>

src/crypto/crypto.go

@@ -21,40 +21,48 @@ func (h Hash) HashFunc() Hash {
 }
 
 const (
-	MD4        Hash = 1 + iota // import golang.org/x/crypto/md4
-	MD5                        // import crypto/md5
-	SHA1                       // import crypto/sha1
-	SHA224                     // import crypto/sha256
-	SHA256                     // import crypto/sha256
-	SHA384                     // import crypto/sha512
-	SHA512                     // import crypto/sha512
-	MD5SHA1                    // no implementation; MD5+SHA1 used for TLS RSA
-	RIPEMD160                  // import golang.org/x/crypto/ripemd160
-	SHA3_224                   // import golang.org/x/crypto/sha3
-	SHA3_256                   // import golang.org/x/crypto/sha3
-	SHA3_384                   // import golang.org/x/crypto/sha3
-	SHA3_512                   // import golang.org/x/crypto/sha3
-	SHA512_224                 // import crypto/sha512
-	SHA512_256                 // import crypto/sha512
+	MD4         Hash = 1 + iota // import golang.org/x/crypto/md4
+	MD5                         // import crypto/md5
+	SHA1                        // import crypto/sha1
+	SHA224                      // import crypto/sha256
+	SHA256                      // import crypto/sha256
+	SHA384                      // import crypto/sha512
+	SHA512                      // import crypto/sha512
+	MD5SHA1                     // no implementation; MD5+SHA1 used for TLS RSA
+	RIPEMD160                   // import golang.org/x/crypto/ripemd160
+	SHA3_224                    // import golang.org/x/crypto/sha3
+	SHA3_256                    // import golang.org/x/crypto/sha3
+	SHA3_384                    // import golang.org/x/crypto/sha3
+	SHA3_512                    // import golang.org/x/crypto/sha3
+	SHA512_224                  // import crypto/sha512
+	SHA512_256                  // import crypto/sha512
+	BLAKE2s_256                 // import golang.org/x/crypto/blake2s
+	BLAKE2b_256                 // import golang.org/x/crypto/blake2b
+	BLAKE2b_384                 // import golang.org/x/crypto/blake2b
+	BLAKE2b_512                 // import golang.org/x/crypto/blake2b
 	maxHash
 )
 
 var digestSizes = []uint8{
-	MD4:        16,
-	MD5:        16,
-	SHA1:       20,
-	SHA224:     28,
-	SHA256:     32,
-	SHA384:     48,
-	SHA512:     64,
-	SHA512_224: 28,
-	SHA512_256: 32,
-	SHA3_224:   28,
-	SHA3_256:   32,
-	SHA3_384:   48,
-	SHA3_512:   64,
-	MD5SHA1:    36,
-	RIPEMD160:  20,
+	MD4:         16,
+	MD5:         16,
+	SHA1:        20,
+	SHA224:      28,
+	SHA256:      32,
+	SHA384:      48,
+	SHA512:      64,
+	SHA512_224:  28,
+	SHA512_256:  32,
+	SHA3_224:    28,
+	SHA3_256:    32,
+	SHA3_384:    48,
+	SHA3_512:    64,
+	MD5SHA1:     36,
+	RIPEMD160:   20,
+	BLAKE2s_256: 32,
+	BLAKE2b_256: 32,
+	BLAKE2b_384: 48,
+	BLAKE2b_512: 64,
 }
 
 // Size returns the length, in bytes, of a digest resulting from the given hash