Add a PKCS#8 DER property to private keys #372
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Motivation: PKCS#8 is pretty widely used. Currently getting a key in PKCS#8 DER representations requires goining through a PKCS8 PEM document and then get its DER bytes. Modifications: Add a computed property to RSA private keys that calls into BoringSSL or Security.framework to get the PKCS8 DER representation of the key. ECDH keys use the existing derRepresentation property to provide a property of the same name. A small ASN1 encoder adds the functionality to ed25519/x25519 keys. Result: The representation can be accessed directly.
Lukasa
reviewed
Jun 30, 2025
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| @available(iOS 14.0, macOS 11.0, watchOS 7.0, tvOS 14.0, *) | ||
| extension P521.Signing.PrivateKey { | ||
| public var pkcs8DERRepresentation: Data { |
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Do you mind adding doc comments to all of these?
| // Identifies the key agreement algorithm X25519. | ||
| // | ||
| // This identifier is defined in RFC 8410 | ||
| public static let idX25519: ASN1ObjectIdentifier = [1, 3, 101, 110] |
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Let's not make these public, we don't need to.
| self.backing.pemRepresentation | ||
| } | ||
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| public var pkcs8DERRepresentation: Data { |
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Let's add documentation to this as well.
Co-authored-by: Cory Benfield <lukasa@apple.com>
Lukasa
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Jul 2, 2025
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Lukasa
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Very nice, thanks @josephnoir! ✨
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Motivation
PKCS#8 is pretty widely used. Currently getting a key in PKCS#8 DER representations requires going through a PKCS8 PEM document and then get its DER bytes.
Modifications
Add a computed property to RSA private keys that calls into BoringSSL or Security.framework to get the PKCS8 DER representation of the key.
ECDH keys use the existing
derRepresentationproperty to provide a property of the same name.A small ASN1 encoder adds the functionality to ed25519/x25519 keys.
Result
The representation can be accessed directly.
The identifiers for MLKEM are still a draft. As such MLKEM is not included in the PR.