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auth: add the caching sha2 algorithm for authentication (#1232)
This allows validating passwords against the `authentication_string` data that MySQL stores for caching_sha2 passwords. Related: - pingcap/tidb#9411
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@@ -2,4 +2,5 @@ bin/ | |
| y.go | ||
| *.output | ||
| .idea/ | ||
| .vscode/ | ||
| coverage.txt | ||
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| // Copyright 2021 PingCAP, Inc. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
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| package auth | ||
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| // Resources: | ||
| // - https://dev.mysql.com/doc/refman/8.0/en/caching-sha2-pluggable-authentication.html | ||
| // - https://dev.mysql.com/doc/dev/mysql-server/latest/page_caching_sha2_authentication_exchanges.html | ||
| // - https://dev.mysql.com/doc/dev/mysql-server/latest/namespacesha2__password.html | ||
| // - https://www.akkadia.org/drepper/SHA-crypt.txt | ||
| // - https://dev.mysql.com/worklog/task/?id=9591 | ||
| // | ||
| // CREATE USER 'foo'@'%' IDENTIFIED BY 'foobar'; | ||
| // SELECT HEX(authentication_string) FROM mysql.user WHERE user='foo'; | ||
| // 24412430303524031A69251C34295C4B35167C7F1E5A7B63091349503974624D34504B5A424679354856336868686F52485A736E4A733368786E427575516C73446469496537 | ||
| // | ||
| // Format: | ||
| // Split on '$': | ||
| // - digest type ("A") | ||
| // - iterations (divided by ITERATION_MULTIPLIER) | ||
| // - salt+hash | ||
| // | ||
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| import ( | ||
| "bytes" | ||
| "crypto/rand" | ||
| "crypto/sha256" | ||
| "errors" | ||
| "fmt" | ||
| "strconv" | ||
| ) | ||
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| const ( | ||
| MIXCHARS = 32 | ||
| SALT_LENGTH = 20 | ||
| ITERATION_MULTIPLIER = 1000 | ||
| ) | ||
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| func b64From24bit(b []byte, n int) []byte { | ||
| b64t := []byte("./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz") | ||
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| w := (int64(b[0]) << 16) | (int64(b[1]) << 8) | int64(b[2]) | ||
| ret := make([]byte, 0, n) | ||
| for n > 0 { | ||
| n-- | ||
| ret = append(ret, b64t[w&0x3f]) | ||
| w >>= 6 | ||
| } | ||
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| return ret | ||
| } | ||
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| func sha256crypt(plaintext string, salt []byte, iterations int) string { | ||
| // Numbers in the comments refer to the description of the algorithm on https://www.akkadia.org/drepper/SHA-crypt.txt | ||
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| // 1, 2, 3 | ||
| tmpA := sha256.New() | ||
| tmpA.Write([]byte(plaintext)) | ||
| tmpA.Write(salt) | ||
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| // 4, 5, 6, 7, 8 | ||
| tmpB := sha256.New() | ||
| tmpB.Write([]byte(plaintext)) | ||
| tmpB.Write(salt) | ||
| tmpB.Write([]byte(plaintext)) | ||
| sumB := tmpB.Sum(nil) | ||
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| // 9, 10 | ||
| var i int | ||
| for i = len(plaintext); i > MIXCHARS; i -= MIXCHARS { | ||
| tmpA.Write(sumB[:MIXCHARS]) | ||
| } | ||
| tmpA.Write(sumB[:i]) | ||
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| // 11 | ||
| for i = len(plaintext); i > 0; i >>= 1 { | ||
| if i%2 == 0 { | ||
| tmpA.Write([]byte(plaintext)) | ||
| } else { | ||
| tmpA.Write(sumB) | ||
| } | ||
| } | ||
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| // 12 | ||
| sumA := tmpA.Sum(nil) | ||
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| // 13, 14, 15 | ||
| tmpDP := sha256.New() | ||
| for range []byte(plaintext) { | ||
| tmpDP.Write([]byte(plaintext)) | ||
| } | ||
| sumDP := tmpDP.Sum(nil) | ||
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| // 16 | ||
| p := make([]byte, 0, sha256.Size) | ||
| for i = len(plaintext); i > 0; i -= MIXCHARS { | ||
| if i > MIXCHARS { | ||
| p = append(p, sumDP...) | ||
| } else { | ||
| p = append(p, sumDP[0:i]...) | ||
| } | ||
| } | ||
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| // 17, 18, 19 | ||
| tmpDS := sha256.New() | ||
| for i = 0; i < 16+int(sumA[0]); i++ { | ||
| tmpDS.Write(salt) | ||
| } | ||
| sumDS := tmpDS.Sum(nil) | ||
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| // 20 | ||
| s := []byte{} | ||
| for i = len(salt); i > 0; i -= MIXCHARS { | ||
| if i > MIXCHARS { | ||
| s = append(s, sumDS...) | ||
| } else { | ||
| s = append(s, sumDS[0:i]...) | ||
| } | ||
| } | ||
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| // 21 | ||
| tmpC := sha256.New() | ||
| var sumC []byte | ||
| for i = 0; i < iterations; i++ { | ||
| tmpC.Reset() | ||
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| if i&1 != 0 { | ||
| tmpC.Write(p) | ||
| } else { | ||
| tmpC.Write(sumA) | ||
| } | ||
| if i%3 != 0 { | ||
| tmpC.Write(s) | ||
| } | ||
| if i%7 != 0 { | ||
| tmpC.Write(p) | ||
| } | ||
| if i&1 != 0 { | ||
| tmpC.Write(sumA) | ||
| } else { | ||
| tmpC.Write(p) | ||
| } | ||
| sumC = tmpC.Sum(nil) | ||
| copy(sumA, tmpC.Sum(nil)) | ||
| } | ||
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| // 22 | ||
| buf := bytes.Buffer{} | ||
| buf.Grow(100) // FIXME | ||
| buf.Write([]byte{'$', 'A', '$'}) | ||
| rounds := fmt.Sprintf("%03d", iterations/ITERATION_MULTIPLIER) | ||
| buf.Write([]byte(rounds)) | ||
| buf.Write([]byte{'$'}) | ||
| buf.Write(salt) | ||
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| buf.Write(b64From24bit([]byte{sumC[0], sumC[10], sumC[20]}, 4)) | ||
| buf.Write(b64From24bit([]byte{sumC[21], sumC[1], sumC[11]}, 4)) | ||
| buf.Write(b64From24bit([]byte{sumC[12], sumC[22], sumC[2]}, 4)) | ||
| buf.Write(b64From24bit([]byte{sumC[3], sumC[13], sumC[23]}, 4)) | ||
| buf.Write(b64From24bit([]byte{sumC[24], sumC[4], sumC[14]}, 4)) | ||
| buf.Write(b64From24bit([]byte{sumC[15], sumC[25], sumC[5]}, 4)) | ||
| buf.Write(b64From24bit([]byte{sumC[6], sumC[16], sumC[26]}, 4)) | ||
| buf.Write(b64From24bit([]byte{sumC[27], sumC[7], sumC[17]}, 4)) | ||
| buf.Write(b64From24bit([]byte{sumC[18], sumC[28], sumC[8]}, 4)) | ||
| buf.Write(b64From24bit([]byte{sumC[9], sumC[19], sumC[29]}, 4)) | ||
| buf.Write(b64From24bit([]byte{0, sumC[31], sumC[30]}, 3)) | ||
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| return buf.String() | ||
| } | ||
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| // Checks if a MySQL style caching_sha2 authentication string matches a password | ||
| func CheckShaPassword(pwhash []byte, password string) (bool, error) { | ||
| pwhash_parts := bytes.Split(pwhash, []byte("$")) | ||
| if len(pwhash_parts) != 4 { | ||
| return false, errors.New("failed to decode hash parts") | ||
| } | ||
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| hash_type := string(pwhash_parts[1]) | ||
| if hash_type != "A" { | ||
| return false, errors.New("digest type is incompatible") | ||
| } | ||
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| iterations, err := strconv.Atoi(string(pwhash_parts[2])) | ||
| if err != nil { | ||
| return false, errors.New("failed to decode iterations") | ||
| } | ||
| iterations = iterations * ITERATION_MULTIPLIER | ||
| salt := pwhash_parts[3][:SALT_LENGTH] | ||
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| newHash := sha256crypt(password, salt, iterations) | ||
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| return bytes.Equal(pwhash, []byte(newHash)), nil | ||
| } | ||
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| func NewSha2Password(pwd string) string { | ||
| salt := make([]byte, SALT_LENGTH) | ||
| rand.Read(salt) | ||
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| return sha256crypt(pwd, salt, 5*ITERATION_MULTIPLIER) | ||
| } |
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