checking in for the night.

key generation should be done, need to finish packing/formatting.

also need to start on moduli generation.

TODO

@@ -1,3 +1,4 @@
--sshkeys (need to figure out generation process)
+-sshkeys (see ref/<type>/parse_poc_<keytype>.go for POC)
+--hostkeys (https://security.stackexchange.com/questions/211106/what-is-the-difference-between-host-and-client-ssh-key-generation)
 -moduli dhparams generation (dh.c? moduli.c?)
 --ssh-keygen.c, ~L3565

moduli/const.go

@@ -0,0 +1 @@
+package moduli

moduli/func.go

@@ -0,0 +1 @@
+package moduli

moduli/main.go

@@ -0,0 +1,5 @@
+package moduli
+
+func main() {
+
+}

moduli/ref/sources

@@ -0,0 +1,6 @@
+https://man7.org/linux/man-pages/man5/moduli.5.html
+https://security.stackexchange.com/questions/41941/consequences-of-tampered-etc-ssh-moduli
+https://access.redhat.com/blogs/766093/posts/2177481
+https://security.stackexchange.com/a/113058
+https://github.com/Luzifer/go-dhparam
+https://github.com/mimoo/test_DHparams

moduli/struct.go

@@ -0,0 +1 @@
+package moduli

sshkeys/const.go

@@ -17,6 +17,10 @@ const (
 	defRounds     uint32 = 100
 	defRSABitSize uint32 = 4096
 	defSaltLen    int    = 16
+	// bcrypt_pbkdf maxes out at 32 for private key gen (sk is actually 64; sk+pk)
+	// But per OpenSSH code, we pass a key len of kdfKeyLen + len(salt)
+	kdfKeyLen int = 32
+	kdfSplit  int = 32
 )
 
 // Cipher names. I believe only AES256-CTR is supported upstream currently.
@@ -52,6 +56,9 @@ const (
 // Key/Block sizes.
 const (
 	keyEd25519 uint32 = 32
+	// Is this correct? Based on PROTOCOL.key's "padlen % 255", it seems to be.
+	blockPad     uint32 = 255
 	blockEd25519 uint32 = 16
+	// Blocksize for RSA depends on key bits, I think.
 	blockNull uint32 = 8
 )

sshkeys/ed25519.go

@@ -0,0 +1,24 @@
+package sshkeys
+
+import (
+	"crypto/ed25519"
+)
+
+func (k *SSHPrivKey) generateEd25519() error {
+	if k.Key != nil || k.PublicKey.Key != nil {
+		return nil // Just no-op; already generated.
+	}
+	// We cast "pk" (public key) to _ because it's an interface{} that we can't seem to
+	// assert to []byte. I've tried iterating, a type assertion, initializing,... nada.
+	// Luckily it's at a fixed half of the secret key.
+	if _, s, err := ed25519.GenerateKey(nil); err != nil {
+		return err
+	} else {
+		k.Key = s
+		ks := len(s) - ed25519.PublicKeySize
+		k.PublicKey.Key = s[ks:]
+		k.BitSize = ed25519Len
+		k.PublicKey.KeyType = KeyEd25519
+	}
+	return nil
+}

sshkeys/func.go

@@ -1,6 +1,9 @@
 package sshkeys
 
 import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
 	"crypto/rand"
 	"errors"
 	"fmt"
@@ -52,7 +55,7 @@ func (k *EncryptedSSHKeyV1) Generate(force bool) error {
 	if err := k.validate(); err != nil {
 		return err
 	}
-	if k.PrivateKeys != nil && !force {
+	if len(k.Keys) > 0 && !force {
 		return nil // Already generated.
 	}
 	if k.KDFOpts.Salt == nil {
@@ -64,10 +67,7 @@ func (k *EncryptedSSHKeyV1) Generate(force bool) error {
 	if k.KDFOpts.Rounds == 0 {
 		k.KDFOpts.Rounds = defRounds
 	}
-	if k.DefKeyType == KeyRsa && k.BitSize == 0 {
-		k.BitSize = defRSABitSize
-	} else if k.DefKeyType == KeyEd25519 {
-		k.BitSize = ed25519Len
+	if k.DefKeyType == KeyEd25519 {
 		k.KeySize = keyEd25519
 		k.BlockSize = blockEd25519
 	}
@@ -80,25 +80,95 @@ func (k *EncryptedSSHKeyV1) Generate(force bool) error {
 	if _, err := rand.Read(pk.Checksum); err != nil {
 		return err
 	}
-	// Upstream only currently supports bcrypt_pbkdf ("bcrypt").
-	// This should always eval to true, but is here for future planning in case other KDF are implemented.
-	if k.KDFName == KdfBcrypt {
-		if pk.Key, err = bcrypt_pbkdf.Key(k.Passphrase, k.KDFOpts.Salt, int(k.KDFOpts.Rounds), int(k.KeySize)); err != nil {
+	switch k.DefKeyType {
+	case KeyRsa:
+		if err := pk.generateRsa(); err != nil {
 			return err
 		}
+	case KeyEd25519:
+		if err := pk.generateEd25519(); err != nil {
+			return err
 		}
-
+	default:
+		return errors.New("unknown key type; could not generate private/public keypair")
+	}
+	k.Keys = append(k.Keys, pk)
+	// We also need an encrypter/decrypter since this is an encrypted key.
+	// Upstream only currently supports bcrypt_pbkdf ("bcrypt").
+	// This should always eval to true, but is here for future planning in case other KDF are implemented.
+	switch k.KDFName {
+	case KdfBcrypt:
+		if k.Crypt.CryptKey, err = bcrypt_pbkdf.Key(k.Passphrase, k.KDFOpts.Salt, int(k.KDFOpts.Rounds), kdfKeyLen+len(k.KDFOpts.Salt)); err != nil {
+			return err
+		} else {
+			k.Crypt.PrivateKey = k.Crypt.CryptKey[0:kdfSplit]
+			k.Crypt.CryptSalt = k.Crypt.CryptKey[kdfSplit:]
+		}
+	default:
+		return errors.New("could not find KDF")
+	}
+	switch k.CipherName {
+	case CipherAes256Ctr:
+		if k.Crypt.Cipher, err = aes.NewCipher(k.Crypt.PrivateKey); err != nil {
+			return err
+		} else {
+			k.Crypt.Stream = cipher.NewCTR(k.Crypt.Cipher, k.Crypt.CryptSalt)
+			// Can then be used as k.Crypt.Stream.XORKeyStream(dst []byte, src []byte)
+		}
+	default:
+		return errors.New("could not find Cipher")
+	}
+	k.build()
 	return nil
 }
 
 func (k *SSHKeyV1) validate() error {
-	return nil
-}
-
-func (k *SSHKeyV1) GeneratePrivate(force bool) error {
-	k.validate()
-	if k.PrivateKeys != nil && !force {
-		return nil // Already generated.
+	var validKT bool
+	for _, v := range allowed_keytypes {
+		if v == k.DefKeyType {
+			validKT = true
+		}
+	}
+	if !validKT {
+		return errors.New("invalid DefKeyType specified")
 	}
 	return nil
 }
+
+func (k *SSHKeyV1) Generate(force bool) error {
+	if len(k.Keys) > 0 && !force {
+		return nil // Already generated.
+	}
+	if k.DefKeyType == KeyEd25519 {
+		k.KeySize = keyEd25519
+		k.BlockSize = blockEd25519
+	}
+	// Currently, OpenSSH has an option for multiple private keys. However, it is hardcoded to 1.
+	// If multiple key support is added in the future, will need to re-tool how I do this, perhaps, in the future. TODO.
+	pk := SSHPrivKey{
+		Comment: fmt.Sprintf("Autogenerated via SSHSecure (%v)", projUrl),
+	}
+	pk.Checksum = make([]byte, 4)
+	if _, err := rand.Read(pk.Checksum); err != nil {
+		return err
+	}
+	switch k.DefKeyType {
+	case KeyRsa:
+		if err := pk.generateRsa(); err != nil {
+			return err
+		}
+	case KeyEd25519:
+		if err := pk.generateEd25519(); err != nil {
+			return err
+		}
+	default:
+		return errors.New("unknown key type; could not generate private/public keypair")
+	}
+	k.Keys = append(k.Keys, pk)
+	k.build()
+	return nil
+}
+
+func (k *SSHKeyV1) build() {
+	// We actually assemble the key buffer here. Translation to bytes where needed, case switches (ED25519 vs. RSA), etc.
+}

sshkeys/interface.go

@@ -1,6 +0,0 @@
-package sshkeys
-
-type OpenSSHKeypair interface {
-	GeneratePrivate(force bool) error
-	GeneratePublic(force bool) error
-}

sshkeys/ref/encrypted/parse_poc_rsa.go

@@ -1,10 +1,13 @@
 package main
 
 import (
-	`crypto/cipher`
-	`crypto/rsa`
-	`encoding/hex`
-	`fmt`
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rsa"
+	"encoding/hex"
+	"fmt"
+
+	"github.com/dchest/bcrypt_pbkdf"
 )
 
 // ssh-keygen -f /tmp/tmp2xzvpjhn -q -o -t rsa -b 4096 -C "This is a comment string" -N test -a 100
@@ -380,23 +383,37 @@ bc2a63a20ebb309cc6f3e65db301a058b8dace07e71b38f3f3595433f69b198f
 func main() {
 	const (
 		passphrase string = "test"
-		rounds         int    = 100
+		saltLen    int    = 16  // 3.0.0.0
+		rounds     int    = 100 // 3.0.0.1
 		keySize    int    = 4096
-		lenPlain       int    = 160
-		publicExponent int    = 65537
+		crtLen     int    = 256   // 4.0.1.4
+		dLen       int    = 512   // 4.0.1.3
+		e          int    = 65537 // 4.0.0.1
+		nLen       int    = 513   // 4.0.0.2
+		pLen       int    = 257   // 4.0.1.5
+		qLen       int    = 257   // 4.0.1.6
+		dataLen    int    = 1872  // 4.0.1
 	)
 	var salt []byte
 	var bcryptKey []byte
-	var sk []byte
-	var pk []byte
-	var pubkey rsa.PublicKey
+	var crt []byte
+	var d []byte
+	var n []byte
+	var p []byte
+	var q []byte
 	var key rsa.PrivateKey
 	var decrypted []byte
 	var aesCtx cipher.Block
 	var encData []byte
 
-	decrypted = make([]byte, lenPlain)
-	encData = make([]byte, lenPlain)
+	crt = make([]byte, crtLen)
+	d = make([]byte, dLen)
+	n = make([]byte, nLen)
+	p = make([]byte, pLen)
+	q = make([]byte, qLen)
+	decrypted = make([]byte, dataLen)
+	encData = make([]byte, dataLen)
+	salt = make([]byte, saltLen)
 
 	// Import salt
 	if s, err := hex.DecodeString("07d4b07c0b128348916488008d6e130b"); err != nil {
@@ -474,11 +491,64 @@ func main() {
 		encData = b
 	}
 
-	// RSA keys
-	// This is used to validate decrypted keys.
-	if rk, err := hex.DecodeString(""); err != nil {
+	// Bcrypt_pbkdf derivation (used for deriving decryption key for AES encrypted private key)
+	if k, err := bcrypt_pbkdf.Key([]byte(passphrase), salt, rounds, 32+16); err != nil {
 		fmt.Println(err)
+		return
 	} else {
-		key = rk
+		bcryptKey = k
 	}
+	realBcryptKey := bcryptKey[0:32]
+	realIV := bcryptKey[32:]
+
+	// N
+	if b, err := hex.DecodeString(
+		"00b7cec04601ce2a12f0c924cb9a30eb990066812cb14369193f30b2b9fdd4af" +
+			"cb300c918f2a77d64410f3617ae7c8ca318c257d3c4df4e2c4108bbbe93a8689" +
+			"4ba14b3575f2f72150bc381dcbfb742c7a196866fd3184ace96761adda0fc299" +
+			"2f6c866d7569919fc22d9c4bf0de405a8c76d519aa2a5329dc6825777229a5d0" +
+			"b753a7825a89b95275f9c025e215343c6c88cd6690a221f8ae9ef675ee464dc7" +
+			"d118da410507ea5d6b6489dd60afd8a6646492db3e279f1a78240db8abbda6c5" +
+			"0714c9636650a72081e7fa5d472c1428b07eae5d15b64ea1e2a7508512fe9ab6" +
+			"55f86a313486d3cca1dd8e90acc5c9fba4d6e767507fbab9f3a7f68c748142af" +
+			"2a3701d31a8a9b7511958aa77187ba702ed934d385afcee42380e95e0e7e9bc0" +
+			"f4d23367fc770374167b7f0926fb6fdb6d05aad1cfd191824845b014e18153bf" +
+			"0d1d3c3b1fadbb25a3f1d151f9b684633d8c1690fcd8cad05aac2aeb23dbf19a" +
+			"37e480a008910319c116d47bd924b39942543b88a0f6127952b2d8e1290f3029" +
+			"f542aebe9c0c8e36cf3296865cd6643c8924d566ebf4971809399a1ac096fe1e" +
+			"dc3b5f871bf5ef0b4d44e0ea27620d205142e0bfcf677b4db025532121a3f074" +
+			"5aa4d0586331733257855a5cecbe3ac4403d04ff0cc0c58b7c04904b402125c2" +
+			"bc2a63a20ebb309cc6f3e65db301a058b8dace07e71b38f3f3595433f69b198f" +
+			"07",
+	); err != nil {
+		fmt.Println(err)
+		return
+	} else {
+		n = b
+	}
+
+	// Decrypter
+	if a, err := aes.NewCipher(realBcryptKey); err != nil {
+		fmt.Println(err)
+		return
+	} else {
+		aesCtx = a
+	}
+
+	// Actual cipher setup. AES256-CTR
+	decryptor := cipher.NewCTR(aesCtx, realIV)
+	decryptor.XORKeyStream(decrypted, encData)
+
+	// Print comparisons
+	fmt.Printf("Salt: %v\n", hex.EncodeToString(salt))
+	fmt.Printf("Bcrypt key: %v\n", hex.EncodeToString(bcryptKey))
+	fmt.Printf("CRT: %v\n", hex.EncodeToString(crt))
+	fmt.Printf("d: %v\n", hex.EncodeToString(d))
+	fmt.Printf("n: %v\n", hex.EncodeToString(n))
+	fmt.Printf("p: %v\n", hex.EncodeToString(p))
+	fmt.Printf("q: %v\n", hex.EncodeToString(q))
+	fmt.Printf("key: %v\n", key)
+	// var aesCtx cipher.Block
+	fmt.Printf("encData: %v\n", hex.EncodeToString(encData))
+	fmt.Printf("Decrypted?: %v\n", hex.EncodeToString(decrypted))
 }

sshkeys/ref/sources

@@ -1,10 +1,12 @@
-https://peterlyons.com/problog/2017/12/openssh-ed25519-private-key-file-format/
 https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.key
 	canonical: https://cvsweb.openbsd.org/src/usr.bin/ssh/PROTOCOL.key?annotate=HEAD
+https://peterlyons.com/problog/2017/12/openssh-ed25519-private-key-file-format/
 https://stackoverflow.com/a/56300901/733214
 https://stackoverflow.com/a/59283692/733214
 https://coolaj86.com/articles/the-openssh-private-key-format/
 https://coolaj86.com/articles/the-ssh-public-key-format/
+https://coolaj86.com/articles/openssh-vs-openssl-key-formats/
+https://coolaj86.com/articles/ssh-pubilc-key-fingerprints/
 https://crypto.stackexchange.com/a/40910
 https://flak.tedunangst.com/post/new-openssh-key-format-and-bcrypt-pbkdf
 ("(Technical note: PBKDF2, aka PKCS #5, supports pluggable hash functions, though in practice everybody uses HMAC-SHA1. The bcrypt pbkdf essentially is PBKDF2, but with bcrypt plugged into it instead.)"
@@ -12,6 +14,21 @@ http://www.tedunangst.com/flak/post/bcrypt-pbkdf
 https://xorhash.gitlab.io/xhblog/0010.html
 https://blog.rebased.pl/2020/02/10/ssh-key-internals.html
 https://blog.rebased.pl/2020/03/24/basic-key-security.html
+https://github.com/pwnedkeys/openssl-additions/blob/master/lib/openssl/ssh_pkey.rb
+https://stackoverflow.com/a/25181584/733214
+https://crypto.stackexchange.com/a/68732
+
+RSA:
+d: 512
+n: 512
+p: 256
+q: 256
+QInv: 256
+d: 4.0.1.3.0
+n: 4.0.0.2.0, 4.0.1.2.1.0 (prefix nullbyte)
+p: 4.0.1.5.0 (prefix nullbyte)
+q: 4.0.1.6.0 (prefix nullbyte)
+QInv: 4.0.1.4.0
 
 ## UPSTREAM
 https://github.com/openssh/openssh-portable/blob/master/sshkey.c

sshkeys/rsa.go

@@ -0,0 +1,23 @@
+package sshkeys
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+)
+
+func (k *SSHPrivKey) generateRsa() error {
+	if k.BitSize == 0 {
+		k.BitSize = defRSABitSize
+	}
+	if k.Key != nil || k.PublicKey.Key != nil {
+		return nil // A no-op; key already exists.
+	}
+	if sk, err := rsa.GenerateKey(rand.Reader, int(k.BitSize)); err != nil {
+		return err
+	} else {
+		k.Key = sk // See https://golang.org/pkg/crypto/rsa/#PrivateKey
+		k.PublicKey.KeyType = KeyRsa
+		k.PublicKey.Key = k.Key.PublicKey
+	}
+	return nil
+}

sshkeys/struct.go

@@ -1,13 +1,29 @@
 package sshkeys
 
+import (
+	"bytes"
+	"crypto/cipher"
+)
+
 // EncryptedSSHKeyV1 represents an encrypted private key.
 type EncryptedSSHKeyV1 struct {
 	SSHKeyV1
 	CipherName string
+	Crypt      SSHCrypt
 	KDFOpts    SSHKDFOpts
 	Passphrase []byte
 }
 
+// SSHEncryptionKey contains the PublicKey and PrivateKey bytes (as derived by KDF, different from the actual SSH keypair),
+// the Cipher, and the stream.
+type SSHCrypt struct {
+	Stream     cipher.Stream
+	Cipher     cipher.Block
+	CryptSalt  []byte
+	PrivateKey []byte
+	CryptKey   []byte
+}
+
 // SSHKDFOpts contains a set of KDF options.
 type SSHKDFOpts struct {
 	Salt   []byte // Also referred to as IV (initialization vector). (https://en.wikipedia.org/wiki/Initialization_vector)
@@ -19,26 +35,28 @@ type SSHKDFOpts struct {
 // Patch your shit.
 type SSHKeyV1 struct {
 	Magic      string
-	BitSize     uint32
 	DefKeyType string
 	KDFName    string
 	KeySize    uint32
 	BlockSize  uint32
-	PublicKeys  []SSHPubKey
-	PrivateKeys []SSHPrivKey
+	Keys       []SSHPrivKey // 1 by default.
+	Buffer     bytes.Buffer
 }
 
 // SSHPubKey contains the Public key of an SSH Keypair.
 type SSHPubKey struct {
-	PrivateKey *SSHPrivKey
 	KeyType string
-	Key        []byte
+	Key     interface{}
 }
 
 // SSHPrivKey contains the Private key of an SSH Keypair.
 type SSHPrivKey struct {
 	PublicKey *SSHPubKey
-	Key       []byte
+	BitSize   uint32
+	Key       interface{}
+	// ED25519 keys are actually "sk + pk", where sk is the secret key and pk is the pubkey.
+	// We store that here.
+	KeyAlt   []byte
 	Checksum []byte
 	Comment  string
 }