x509.MarshalPKIXPublicKey vs x509.MarshalPKCS1PublicKey

The Go standard library provides two functions for serializing public keys to DER-encoded formats: x509.MarshalPKIXPublicKey and x509.MarshalPKCS1PublicKey.

DER-Encoded PKIX Format

DER (Distinguished Encoding Rules) is a specific encoding scheme for ASN.1 (Abstract Syntax Notation One) data. ASN.1 is a language for defining data structures used in cryptography, while DER is a mechanism for representing those structures in bytes.

PKIX (Public Key Infrastructure X.509) is an extension of the X.509 standard that includes support for multiple public key algorithms. A PKIX public key certificate contains a public key and other information, such as the issuer and subject names, in DER-encoded ASN.1 format.

MarshalPKIXPublicKey

x509.MarshalPKIXPublicKey serializes a public key to DER-encoded PKIX format. This format is used in X.509 public key certificates and other applications that support PKIX.

MarshalPKCS1PublicKey

x509.MarshalPKCS1PublicKey converts an RSA public key to PKCS#1, ASN.1 DER form. PKCS#1 is a standard for using RSA public keys in various cryptographic applications. The MarshalPKCS1PublicKey function ensures that the resulting DER-encoded data conforms to the PKCS#1 standard.

Summary

x509.MarshalPKIXPublicKey serializes a public key to DER-encoded PKIX format, which is used in X.509 certificates and other applications that support PKIX. x509.MarshalPKCS1PublicKey converts an RSA public key to PKCS#1, ASN.1 DER form, which is used in applications that require RSA public keys in this specific format.