47 lines
730 B
Go
47 lines
730 B
Go
package jwk
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import (
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"crypto/rsa"
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"encoding/base64"
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"encoding/json"
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"errors"
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"math/big"
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)
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type RSAPublicKeyHeader struct {
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Modulus string `json:"n"`
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Exponent string `json:"e"`
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}
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var (
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ErrUnsupportedPublicExponent = errors.New("Public exponent is not 65537")
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)
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func ParseRSAPublicKey(data []byte) (*rsa.PublicKey, error) {
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var header RSAPublicKeyHeader
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err := json.Unmarshal(data, &header)
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if err != nil {
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return nil, err
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}
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rawN, err := base64.RawURLEncoding.DecodeString(header.Modulus)
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if err != nil {
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return nil, err
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}
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n := new(big.Int).SetBytes(rawN)
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if header.Exponent != "AQAB" {
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return nil, ErrUnsupportedPublicExponent
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}
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key := &rsa.PublicKey{
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N: n,
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E: 65537,
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}
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return key, nil
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}
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