[release-branch.go1] crypto/rsa: add SHA-224 hash prefix

««« backport c6213d8a9118
crypto/rsa: add SHA-224 hash prefix

http://www.rsa.com/rsalabs/node.asp?id=2125:

NOTE: A new OID has been defined for the combination
of the v1.5 signature scheme and the SHA-224 hash function:
        sha224WithRSAEncryption OBJECT IDENTIFIER ::=
Like the other sha*WithRSAEncryption OIDs in PKCS #1 v2.1,
this OID has NULL parameters.
The DigestInfo encoding for SHA-224 (see Section 9.2, Note 1) is:
        (0x)30 2d 30 0d 06 09 60 86 48 01 65 03 04 02 04 05 00 04 1c || H

R=golang-dev, agl
CC=golang-dev
https://golang.org/cl/6208076

»»»

src/pkg/crypto/rsa/pkcs1v15.go

@@ -151,6 +151,7 @@ func nonZeroRandomBytes(s []byte, rand io.Reader) (err error) {
 var hashPrefixes = map[crypto.Hash][]byte{
 	crypto.MD5:       {0x30, 0x20, 0x30, 0x0c, 0x06, 0x08, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, 0x05, 0x00, 0x04, 0x10},
 	crypto.SHA1:      {0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03, 0x02, 0x1a, 0x05, 0x00, 0x04, 0x14},
+	crypto.SHA224:    {0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04, 0x05, 0x00, 0x04, 0x1c},
 	crypto.SHA256:    {0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20},
 	crypto.SHA384:    {0x30, 0x41, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02, 0x05, 0x00, 0x04, 0x30},
 	crypto.SHA512:    {0x30, 0x51, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, 0x05, 0x00, 0x04, 0x40},