github.com/bgentry/go@v0.0.0-20150121062915-6cf5a733d54d/src/crypto/crypto.go (about) 1 // Copyright 2011 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // Package crypto collects common cryptographic constants. 6 package crypto 7 8 import ( 9 "hash" 10 "io" 11 "strconv" 12 ) 13 14 // Hash identifies a cryptographic hash function that is implemented in another 15 // package. 16 type Hash uint 17 18 // HashFunc simply returns the value of h so that Hash implements SignerOpts. 19 func (h Hash) HashFunc() Hash { 20 return h 21 } 22 23 const ( 24 MD4 Hash = 1 + iota // import golang.org/x/crypto/md4 25 MD5 // import crypto/md5 26 SHA1 // import crypto/sha1 27 SHA224 // import crypto/sha256 28 SHA256 // import crypto/sha256 29 SHA384 // import crypto/sha512 30 SHA512 // import crypto/sha512 31 MD5SHA1 // no implementation; MD5+SHA1 used for TLS RSA 32 RIPEMD160 // import golang.org/x/crypto/ripemd160 33 SHA3_224 // import golang.org/x/crypto/sha3 34 SHA3_256 // import golang.org/x/crypto/sha3 35 SHA3_384 // import golang.org/x/crypto/sha3 36 SHA3_512 // import golang.org/x/crypto/sha3 37 maxHash 38 ) 39 40 var digestSizes = []uint8{ 41 MD4: 16, 42 MD5: 16, 43 SHA1: 20, 44 SHA224: 28, 45 SHA256: 32, 46 SHA384: 48, 47 SHA512: 64, 48 SHA3_224: 28, 49 SHA3_256: 32, 50 SHA3_384: 48, 51 SHA3_512: 64, 52 MD5SHA1: 36, 53 RIPEMD160: 20, 54 } 55 56 // Size returns the length, in bytes, of a digest resulting from the given hash 57 // function. It doesn't require that the hash function in question be linked 58 // into the program. 59 func (h Hash) Size() int { 60 if h > 0 && h < maxHash { 61 return int(digestSizes[h]) 62 } 63 panic("crypto: Size of unknown hash function") 64 } 65 66 var hashes = make([]func() hash.Hash, maxHash) 67 68 // New returns a new hash.Hash calculating the given hash function. New panics 69 // if the hash function is not linked into the binary. 70 func (h Hash) New() hash.Hash { 71 if h > 0 && h < maxHash { 72 f := hashes[h] 73 if f != nil { 74 return f() 75 } 76 } 77 panic("crypto: requested hash function #" + strconv.Itoa(int(h)) + " is unavailable") 78 } 79 80 // Available reports whether the given hash function is linked into the binary. 81 func (h Hash) Available() bool { 82 return h < maxHash && hashes[h] != nil 83 } 84 85 // RegisterHash registers a function that returns a new instance of the given 86 // hash function. This is intended to be called from the init function in 87 // packages that implement hash functions. 88 func RegisterHash(h Hash, f func() hash.Hash) { 89 if h >= maxHash { 90 panic("crypto: RegisterHash of unknown hash function") 91 } 92 hashes[h] = f 93 } 94 95 // PublicKey represents a public key using an unspecified algorithm. 96 type PublicKey interface{} 97 98 // PrivateKey represents a private key using an unspecified algorithm. 99 type PrivateKey interface{} 100 101 // Signer is an interface for an opaque private key that can be used for 102 // signing operations. For example, an RSA key kept in a hardware module. 103 type Signer interface { 104 // Public returns the public key corresponding to the opaque, 105 // private key. 106 Public() PublicKey 107 108 // Sign signs msg with the private key, possibly using entropy from 109 // rand. For an RSA key, the resulting signature should be either a 110 // PKCS#1 v1.5 or PSS signature (as indicated by opts). For an (EC)DSA 111 // key, it should be a DER-serialised, ASN.1 signature structure. 112 // 113 // Hash implements the SignerOpts interface and, in most cases, one can 114 // simply pass in the hash function used as opts. Sign may also attempt 115 // to type assert opts to other types in order to obtain algorithm 116 // specific values. See the documentation in each package for details. 117 Sign(rand io.Reader, msg []byte, opts SignerOpts) (signature []byte, err error) 118 } 119 120 // SignerOpts contains options for signing with a Signer. 121 type SignerOpts interface { 122 // HashFunc returns an identifier for the hash function used to produce 123 // the message passed to Signer.Sign, or else zero to indicate that no 124 // hashing was done. 125 HashFunc() Hash 126 }