class OpenSSL::HMAC
OpenSSL::HMAC
allows computing Hash-based Message Authentication Code (HMAC
). It is a type of message authentication code (MAC) involving a hash function in combination with a key. HMAC
can be used to verify the integrity of a message as well as the authenticity.
OpenSSL::HMAC
has a similar interface to OpenSSL::Digest
.
HMAC-SHA256 using one-shot interface¶ ↑
key = "key" data = "message-to-be-authenticated" mac = OpenSSL::HMAC.hexdigest("SHA256", key, data) #=> "cddb0db23f469c8bf072b21fd837149bd6ace9ab771cceef14c9e517cc93282e"
HMAC-SHA256 using incremental interface¶ ↑
data1 = File.binread("file1") data2 = File.binread("file2") key = "key" hmac = OpenSSL::HMAC.new(key, 'SHA256') hmac << data1 hmac << data2 mac = hmac.digest
Public Class Methods
Returns the authentication code as a Base64-encoded string. The digest parameter specifies the digest algorithm to use. This may be a String representing the algorithm name or an instance of OpenSSL::Digest
.
Example¶ ↑
key = 'key' data = 'The quick brown fox jumps over the lazy dog' hmac = OpenSSL::HMAC.base64digest('SHA1', key, data) #=> "3nybhbi3iqa8ino29wqQcBydtNk="
# File openssl/lib/openssl/hmac.rb, line 73 def base64digest(digest, key, data) [digest(digest, key, data)].pack("m0") end
Returns the authentication code as a binary string. The digest parameter specifies the digest algorithm to use. This may be a String representing the algorithm name or an instance of OpenSSL::Digest
.
Example¶ ↑
key = 'key' data = 'The quick brown fox jumps over the lazy dog' hmac = OpenSSL::HMAC.digest('SHA1', key, data) #=> "\xDE|\x9B\x85\xB8\xB7\x8A\xA6\xBC\x8Az6\xF7\n\x90p\x1C\x9D\xB4\xD9"
# File openssl/lib/openssl/hmac.rb, line 35 def digest(digest, key, data) hmac = new(key, digest) hmac << data hmac.digest end
Returns the authentication code as a hex-encoded string. The digest parameter specifies the digest algorithm to use. This may be a String representing the algorithm name or an instance of OpenSSL::Digest
.
Example¶ ↑
key = 'key' data = 'The quick brown fox jumps over the lazy dog' hmac = OpenSSL::HMAC.hexdigest('SHA1', key, data) #=> "de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9"
# File openssl/lib/openssl/hmac.rb, line 54 def hexdigest(digest, key, data) hmac = new(key, digest) hmac << data hmac.hexdigest end
Returns an instance of OpenSSL::HMAC
set with the key and digest algorithm to be used. The instance represents the initial state of the message authentication code before any data has been processed. To process data with it, use the instance method update
with your data as an argument.
Example¶ ↑
key = 'key' instance = OpenSSL::HMAC.new(key, 'SHA1') #=> f42bb0eeb018ebbd4597ae7213711ec60760843f instance.class #=> OpenSSL::HMAC
A note about comparisons¶ ↑
Two instances can be securely compared with ==
in constant time:
other_instance = OpenSSL::HMAC.new('key', 'SHA1') #=> f42bb0eeb018ebbd4597ae7213711ec60760843f instance == other_instance #=> true
static VALUE ossl_hmac_initialize(VALUE self, VALUE key, VALUE digest) { EVP_MD_CTX *ctx; EVP_PKEY *pkey; GetHMAC(self, ctx); StringValue(key); #ifdef HAVE_EVP_PKEY_NEW_RAW_PRIVATE_KEY pkey = EVP_PKEY_new_raw_private_key(EVP_PKEY_HMAC, NULL, (unsigned char *)RSTRING_PTR(key), RSTRING_LENINT(key)); if (!pkey) ossl_raise(eHMACError, "EVP_PKEY_new_raw_private_key"); #else pkey = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, (unsigned char *)RSTRING_PTR(key), RSTRING_LENINT(key)); if (!pkey) ossl_raise(eHMACError, "EVP_PKEY_new_mac_key"); #endif if (EVP_DigestSignInit(ctx, NULL, ossl_evp_get_digestbyname(digest), NULL, pkey) != 1) { EVP_PKEY_free(pkey); ossl_raise(eHMACError, "EVP_DigestSignInit"); } /* Decrement reference counter; EVP_MD_CTX still keeps it */ EVP_PKEY_free(pkey); return self; }
Public Instance Methods
Returns hmac updated with the message to be authenticated. Can be called repeatedly with chunks of the message.
Example¶ ↑
first_chunk = 'The quick brown fox jumps ' second_chunk = 'over the lazy dog' instance.update(first_chunk) #=> 5b9a8038a65d571076d97fe783989e52278a492a instance.update(second_chunk) #=> de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9
Securely compare with another HMAC
instance in constant time.
# File openssl/lib/openssl/hmac.rb, line 6 def ==(other) return false unless HMAC === other return false unless self.digest.bytesize == other.digest.bytesize OpenSSL.fixed_length_secure_compare(self.digest, other.digest) end
Returns the authentication code an a Base64-encoded string.
# File openssl/lib/openssl/hmac.rb, line 17 def base64digest [digest].pack("m0") end
Returns the authentication code an instance represents as a binary string.
Example¶ ↑
instance = OpenSSL::HMAC.new('key', 'SHA1') #=> f42bb0eeb018ebbd4597ae7213711ec60760843f instance.digest #=> "\xF4+\xB0\xEE\xB0\x18\xEB\xBDE\x97\xAEr\x13q\x1E\xC6\a`\x84?"
static VALUE ossl_hmac_digest(VALUE self) { EVP_MD_CTX *ctx; size_t buf_len = EVP_MAX_MD_SIZE; VALUE ret; GetHMAC(self, ctx); ret = rb_str_new(NULL, EVP_MAX_MD_SIZE); if (EVP_DigestSignFinal(ctx, (unsigned char *)RSTRING_PTR(ret), &buf_len) != 1) ossl_raise(eHMACError, "EVP_DigestSignFinal"); rb_str_set_len(ret, (long)buf_len); return ret; }
Returns the authentication code an instance represents as a hex-encoded string.
static VALUE ossl_hmac_hexdigest(VALUE self) { EVP_MD_CTX *ctx; unsigned char buf[EVP_MAX_MD_SIZE]; size_t buf_len = EVP_MAX_MD_SIZE; VALUE ret; GetHMAC(self, ctx); if (EVP_DigestSignFinal(ctx, buf, &buf_len) != 1) ossl_raise(eHMACError, "EVP_DigestSignFinal"); ret = rb_str_new(NULL, buf_len * 2); ossl_bin2hex(buf, RSTRING_PTR(ret), buf_len); return ret; }
static VALUE ossl_hmac_copy(VALUE self, VALUE other) { EVP_MD_CTX *ctx1, *ctx2; rb_check_frozen(self); if (self == other) return self; GetHMAC(self, ctx1); GetHMAC(other, ctx2); if (EVP_MD_CTX_copy(ctx1, ctx2) != 1) ossl_raise(eHMACError, "EVP_MD_CTX_copy"); return self; }
Returns the authentication code as a hex-encoded string. The digest parameter specifies the digest algorithm to use. This may be a String representing the algorithm name or an instance of OpenSSL::Digest
.
Example¶ ↑
key = 'key' data = 'The quick brown fox jumps over the lazy dog' hmac = OpenSSL::HMAC.hexdigest('SHA1', key, data) #=> "de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9"
Returns hmac as it was when it was first initialized, with all processed data cleared from it.
Example¶ ↑
data = "The quick brown fox jumps over the lazy dog" instance = OpenSSL::HMAC.new('key', 'SHA1') #=> f42bb0eeb018ebbd4597ae7213711ec60760843f instance.update(data) #=> de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9 instance.reset #=> f42bb0eeb018ebbd4597ae7213711ec60760843f
static VALUE ossl_hmac_reset(VALUE self) { EVP_MD_CTX *ctx; EVP_PKEY *pkey; GetHMAC(self, ctx); pkey = EVP_PKEY_CTX_get0_pkey(EVP_MD_CTX_get_pkey_ctx(ctx)); if (EVP_DigestSignInit(ctx, NULL, EVP_MD_CTX_get0_md(ctx), NULL, pkey) != 1) ossl_raise(eHMACError, "EVP_DigestSignInit"); return self; }
Returns the authentication code as a hex-encoded string. The digest parameter specifies the digest algorithm to use. This may be a String representing the algorithm name or an instance of OpenSSL::Digest
.
Example¶ ↑
key = 'key' data = 'The quick brown fox jumps over the lazy dog' hmac = OpenSSL::HMAC.hexdigest('SHA1', key, data) #=> "de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9"
Returns hmac updated with the message to be authenticated. Can be called repeatedly with chunks of the message.
Example¶ ↑
first_chunk = 'The quick brown fox jumps ' second_chunk = 'over the lazy dog' instance.update(first_chunk) #=> 5b9a8038a65d571076d97fe783989e52278a492a instance.update(second_chunk) #=> de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9
static VALUE ossl_hmac_update(VALUE self, VALUE data) { EVP_MD_CTX *ctx; StringValue(data); GetHMAC(self, ctx); if (EVP_DigestSignUpdate(ctx, RSTRING_PTR(data), RSTRING_LEN(data)) != 1) ossl_raise(eHMACError, "EVP_DigestSignUpdate"); return self; }