mirror of
https://github.com/edgelesssys/constellation.git
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103 lines
3.1 KiB
Go
103 lines
3.1 KiB
Go
/*
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Copyright (c) Edgeless Systems GmbH
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SPDX-License-Identifier: AGPL-3.0-only
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*/
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// Package crypto provides functions to for cryptography and random numbers.
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package crypto
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import (
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"bytes"
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"crypto/ed25519"
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"crypto/rand"
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"crypto/sha256"
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"crypto/x509"
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"encoding/pem"
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"fmt"
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"io"
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"math/big"
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"golang.org/x/crypto/hkdf"
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"golang.org/x/crypto/ssh"
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)
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const (
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// StateDiskKeyLength is key length in bytes for node state disk.
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StateDiskKeyLength = 32
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// DerivedKeyLengthDefault is the default length in bytes for KMS derived keys.
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DerivedKeyLengthDefault = 32
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// MasterSecretLengthDefault is the default length in bytes for CLI generated master secrets.
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MasterSecretLengthDefault = 32
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// MasterSecretLengthMin is the minimal length in bytes for user provided master secrets.
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MasterSecretLengthMin = 16
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// RNGLengthDefault is the number of bytes used for generating nonces.
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RNGLengthDefault = 32
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// DEKPrefix is the prefix used to prefix DEK IDs. Originally introduced as a requirement for the HKDF info parameter.
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DEKPrefix = "key-"
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// MeasurementSecretKeyID is name used for the measurementSecret DEK.
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MeasurementSecretKeyID = "measurementSecret"
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)
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// DeriveKey derives a key from a secret.
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func DeriveKey(secret, salt, info []byte, length uint) ([]byte, error) {
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hkdf := hkdf.New(sha256.New, secret, salt, info)
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key := make([]byte, length)
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if _, err := io.ReadFull(hkdf, key); err != nil {
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return nil, err
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}
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return key, nil
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}
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// GenerateCertificateSerialNumber generates a random serial number for an X.509 certificate.
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func GenerateCertificateSerialNumber() (*big.Int, error) {
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serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
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return rand.Int(rand.Reader, serialNumberLimit)
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}
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// GenerateRandomBytes reads length bytes from getrandom(2) if available, /dev/urandom otherwise.
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func GenerateRandomBytes(length int) ([]byte, error) {
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nonce := make([]byte, length)
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if _, err := rand.Read(nonce); err != nil {
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return nil, err
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}
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return nonce, nil
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}
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// GenerateEmergencySSHCAKey creates a CA that is used to sign keys for emergency ssh access.
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func GenerateEmergencySSHCAKey(seed []byte) (ssh.Signer, error) {
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_, priv, err := ed25519.GenerateKey(bytes.NewReader(seed))
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if err != nil {
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return nil, err
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}
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ca, err := ssh.NewSignerFromSigner(priv)
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if err != nil {
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return nil, err
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}
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return ca, nil
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}
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// PemToX509Cert takes a list of PEM-encoded certificates, parses the first one and returns it
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// as an x.509 certificate.
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func PemToX509Cert(raw []byte) (*x509.Certificate, error) {
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decoded, _ := pem.Decode(raw)
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if decoded == nil {
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return nil, fmt.Errorf("decoding pem: no PEM data found")
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}
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cert, err := x509.ParseCertificate(decoded.Bytes)
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if err != nil {
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return nil, fmt.Errorf("parsing certificate: %w", err)
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}
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return cert, nil
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}
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// X509CertToPem takes an x.509 certificate and returns it as a PEM-encoded certificate.
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func X509CertToPem(cert *x509.Certificate) ([]byte, error) {
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outWriter := &bytes.Buffer{}
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err := pem.Encode(outWriter, &pem.Block{Type: "CERTIFICATE", Bytes: cert.Raw})
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if err != nil {
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return nil, fmt.Errorf("encode certificate: %w", err)
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}
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return outWriter.Bytes(), nil
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}
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