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[WIP] add support for PBKDF2 for passphrases
Passphrase support currently hardcodes the use of Argon2. This adds support for specifying PBKDF2, for use in environments where FIPS140 compliance is required.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,97 @@ | ||
| // -*- Mode: Go; indent-tabs-mode: t -*- | ||
|
|
||
| /* | ||
| * Copyright (C) 2024 Canonical Ltd | ||
| * | ||
| * This program is free software: you can redistribute it and/or modify | ||
| * it under the terms of the GNU General Public License version 3 as | ||
| * published by the Free Software Foundation. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License | ||
| * along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
| * | ||
| */ | ||
|
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| package pbkdf2 | ||
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| import ( | ||
| "crypto" | ||
| "errors" | ||
| "time" | ||
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| "golang.org/x/crypto/pbkdf2" | ||
| ) | ||
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| const ( | ||
| benchmarkPassword = "foo" | ||
| ) | ||
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| var ( | ||
| benchmarkSalt = []byte("0123456789abcdefghijklmnopqrstuv") | ||
| ) | ||
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| type BenchmarkParams struct { | ||
| TargetDuration time.Duration | ||
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| HashAlg crypto.Hash | ||
| } | ||
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| func Benchmark(params *BenchmarkParams, keyLen int32) (*Params, error) { | ||
| if keyLen < 0 { | ||
| return nil, errors.New("invalid key length") | ||
| } | ||
|
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| outParams := &Params{ | ||
| Iterations: 1000, | ||
| HashAlg: params.HashAlg, | ||
| } | ||
| iterations := outParams.Iterations | ||
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| for i := 1; ; i++ { | ||
| start := time.Now() | ||
| Key(benchmarkPassword, benchmarkSalt, &Params{Iterations: iterations, HashAlg: params.HashAlg}, keyLen) | ||
| duration := time.Now().Sub(start) | ||
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| newIterationsOut := int32(int64(iterations) * int64(params.TargetDuration/duration)) | ||
| if newIterationsOut < outParams.Iterations { | ||
| return outParams, nil | ||
| } | ||
| outParams.Iterations = newIterationsOut | ||
|
|
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| switch { | ||
| case i > 10: | ||
| return nil, errors.New("insufficient progress") | ||
| case duration > 500*time.Millisecond: | ||
| return outParams, nil | ||
| case duration <= 62*time.Millisecond: | ||
| iterations *= 16 | ||
| case duration <= 125*time.Millisecond: | ||
| iterations *= 8 | ||
| case duration <= 250*time.Millisecond: | ||
| iterations *= 4 | ||
| default: | ||
| iterations *= 2 | ||
| } | ||
| } | ||
| } | ||
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| type Params struct { | ||
| Iterations int32 | ||
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| HashAlg crypto.Hash | ||
| } | ||
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| func Key(passphrase string, salt []byte, params *Params, keyLen int32) []byte { | ||
| if params.Iterations < 0 { | ||
| panic("invalid iterations") | ||
| } | ||
| if keyLen < 0 { | ||
| panic("invalid key length") | ||
| } | ||
| return pbkdf2.Key([]byte(passphrase), salt, int(params.Iterations), int(keyLen), params.HashAlg.New) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,26 @@ | ||
| // -*- Mode: Go; indent-tabs-mode: t -*- | ||
|
|
||
| /* | ||
| * Copyright (C) 2024 Canonical Ltd | ||
| * | ||
| * This program is free software: you can redistribute it and/or modify | ||
| * it under the terms of the GNU General Public License version 3 as | ||
| * published by the Free Software Foundation. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License | ||
| * along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
| * | ||
| */ | ||
|
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| package secboot | ||
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| // KDFOptions is an interface for supplying options for different | ||
| // key derivation functions | ||
| type KDFOptions interface { | ||
| kdfParams(keyLen uint32) (*kdfParams, error) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,93 @@ | ||
| // -*- Mode: Go; indent-tabs-mode: t -*- | ||
|
|
||
| /* | ||
| * Copyright (C) 2024 Canonical Ltd | ||
| * | ||
| * This program is free software: you can redistribute it and/or modify | ||
| * it under the terms of the GNU General Public License version 3 as | ||
| * published by the Free Software Foundation. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License | ||
| * along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
| * | ||
| */ | ||
|
|
||
| package secboot | ||
|
|
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| import ( | ||
| "crypto" | ||
| "errors" | ||
| "fmt" | ||
| "math" | ||
| "time" | ||
|
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| "github.com/snapcore/secboot/internal/pbkdf2" | ||
| "golang.org/x/xerrors" | ||
| ) | ||
|
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| const ( | ||
| pbkdf2Type = "pbkdf2" | ||
| ) | ||
|
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| type PBKDF2Options struct { | ||
| TargetDuration time.Duration | ||
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| ForceIterations uint32 | ||
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| HashAlg crypto.Hash | ||
| } | ||
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| func (o *PBKDF2Options) kdfParams(keyLen uint32) (*kdfParams, error) { | ||
| if keyLen > math.MaxInt32 { | ||
| return nil, errors.New("invalid key length") | ||
| } | ||
|
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| switch { | ||
| case o.ForceIterations > 0: | ||
| // The non-benchmarked path. Ensure that ForceIterations | ||
| // fits into an int32 so that it always fits into an int | ||
| switch { | ||
| case int64(o.ForceIterations) > math.MaxInt32: | ||
| return nil, fmt.Errorf("invalid iterations count %d", o.ForceIterations) | ||
| } | ||
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| params := &kdfParams{ | ||
| Type: pbkdf2Type, | ||
| Time: int(o.ForceIterations), // no limit to the time cost. | ||
| Hash: hashAlg(crypto.SHA256), | ||
| } | ||
| if o.HashAlg != crypto.Hash(0) { | ||
| switch o.HashAlg { | ||
| case crypto.SHA1, crypto.SHA224, crypto.SHA256, crypto.SHA384, crypto.SHA512: | ||
| params.Hash = hashAlg(o.HashAlg) | ||
| default: | ||
| return nil, errors.New("invalid hash algorithm") | ||
| } | ||
| } | ||
|
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| return params, nil | ||
| default: | ||
| benchmarkParams := &pbkdf2.BenchmarkParams{ | ||
| TargetDuration: 2 * time.Second, // the default target duration is 2s. | ||
| HashAlg: crypto.SHA256, | ||
| } | ||
| if o.HashAlg != crypto.Hash(0) { | ||
| benchmarkParams.HashAlg = o.HashAlg | ||
| } | ||
|
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| params, err := pbkdf2.Benchmark(benchmarkParams, int32(keyLen)) | ||
| if err != nil { | ||
| return nil, xerrors.Errorf("cannot benchmark KDF: %w", err) | ||
| } | ||
|
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| o = &PBKDF2Options{ | ||
| ForceIterations: uint32(params.Iterations), | ||
| HashAlg: params.HashAlg} | ||
| return o.kdfParams(keyLen) | ||
| } | ||
| } |