如何在Go中从x509证书公钥中获取字符串？

Question

如果我有一个*x509.Certificate对象，如何从中提取公钥base64字符串表示形式？

Answer 1

NOTE: Jump to #3 if you already have the x509.Certificate object.

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You would need to do the following:

1. Decode the PEM with pem.Decode() .

block, _ := pem.Decode([]byte(certPEM))

2. Parse the certificate with x509.ParseCertificate() .

cert, _ := x509.ParseCertificate(block.Bytes)

3. Marshal the Public key with x509.MarshalPKIXPublicKey() .

publicKeyDer, _ := x509.MarshalPKIXPublicKey(cert.PublicKey)

4. Encode it in a PEM encoded structure with pem.EncodeToMemory() .

publicKeyBlock := pem.Block{
    Type:  "PUBLIC KEY",
    Bytes: publicKeyDer,
}
publicKeyPem := string(pem.EncodeToMemory(&publicKeyBlock))

Run it on Go Playground

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You can confirm the result if you copy the certificate in the example to a file cert.pem with the command:

openssl x509 -inform pem -in cert.pem -pubkey -noout

You should get the same result!