dump out a usable private key string too; inspired by Tyson Whitehead

diff --git a/regress/usr.bin/ssh/unittests/sshsig/webauthn.html b/regress/usr.bin/ssh/unittests/sshsig/webauthn.html
index 953041e..1869c8b 100644 (file)
--- a/regress/usr.bin/ssh/unittests/sshsig/webauthn.html
+++ b/regress/usr.bin/ssh/unittests/sshsig/webauthn.html
@@ -37,6 +37,8 @@ Lots of debugging is printed along the way.
 <pre id="enrollresultraw" style="color: #008; font-family: monospace;"></pre>
 <h2>attestationObject</h2>
 <pre id="enrollresultattestobj" style="color: #008; font-family: monospace;"></pre>
+<h2>key handle</h2>
+<pre id="keyhandle" style="color: #008; font-family: monospace;"></pre>
 <h2>authData raw</h2>
 <pre id="enrollresultauthdataraw" style="color: #008; font-family: monospace;"></pre>
 <h2>authData</h2>
@@ -45,6 +47,8 @@ Lots of debugging is printed along the way.
 <pre id="enrollresultpkblob" style="color: #008; font-family: monospace;"></pre>
 <h2>SSH pubkey string</h2>
 <pre id="enrollresultpk" style="color: #008; font-family: monospace;"></pre>
+<h2>SSH private key string</h2>
+<pre id="enrollresultprivkey" style="color: #008; font-family: monospace;"></pre>
 </span>
 <span id="assertsection" style="visibility: hidden;">
 <h2>Assert</h2>
@@ -241,12 +245,16 @@ var SSHMSG = function() {
        this.r = []
 }
 
-SSHMSG.prototype.serialise = function() {
+SSHMSG.prototype.length = function() {
        let len = 0
        for (buf of this.r) {
                len += buf.length
        }
-       let r = new ArrayBuffer(len)
+       return len
+}
+
+SSHMSG.prototype.serialise = function() {
+       let r = new ArrayBuffer(this.length())
        let v = new Uint8Array(r)
        let offset = 0
        for (buf of this.r) {
@@ -281,6 +289,12 @@ SSHMSG.prototype.put = function(v) {
        this.r.push(new Uint8Array(v))
 }
 
+SSHMSG.prototype.putStringRaw = function(v) {
+       let enc = new TextEncoder();
+       let venc = enc.encode(v)
+       this.put(venc)
+}
+
 SSHMSG.prototype.putString = function(v) {
        let enc = new TextEncoder();
        let venc = enc.encode(v)
@@ -392,6 +406,9 @@ function enrollSuccess(result) {
        clientData = u8dec.decode(result.response.clientDataJSON)
        document.getElementById("enrollresultjson").innerText = clientData
 
+       // Show the raw key handle.
+       document.getElementById("keyhandle").innerText = hexdump(result.rawId)
+
        // Decode and show the attestationObject
        document.getElementById("enrollresultraw").innerText = hexdump(result.response.attestationObject)
        let aod = new CBORDecode(result.response.attestationObject)
@@ -417,6 +434,14 @@ function enrollSuccess(result) {
        let pk = "sk-ecdsa-sha2-nistp256@openssh.com " + pk64
        document.getElementById("enrollresultpk").innerText = pk
 
+       // Format a private key too.
+       flags = 0x01 // SSH_SK_USER_PRESENCE_REQD
+       window.rawPrivkey = reformatPrivkey(authData.attestedCredentialData.credentialPublicKey, window.enrollOpts.rp.id, result.rawId, flags)
+       let privkeyFileBlob = privkeyFile(window.rawKey, window.rawPrivkey, window.enrollOpts.user.name, window.enrollOpts.rp.id)
+       let privk64 = btoa(String.fromCharCode(...new Uint8Array(privkeyFileBlob)));
+       let privkey = "-----BEGIN OPENSSH PRIVATE KEY-----\n" + wrapString(privk64, 70) + "-----END OPENSSH PRIVATE KEY-----\n"
+       document.getElementById("enrollresultprivkey").innerText = privkey
+
        // Success: show the assertion form.
        document.getElementById("assertsection").style.visibility = "visible"
 }
@@ -456,7 +481,15 @@ function decodeAuthenticatorData(authData, expectCred) {
        return r
 }
 
-function reformatPubkey(pk, rpid) {
+function wrapString(s, l) {
+       ret = ""
+       for (i = 0; i < s.length; i += l) {
+               ret += s.slice(i, i + l) + "\n"
+       }
+       return ret
+}
+
+function checkPubkey(pk) {
        // pk is in COSE format. We only care about a tiny subset.
        if (pk[1] != 2) {
                console.dir(pk)
@@ -471,6 +504,10 @@ function reformatPubkey(pk, rpid) {
        if (pk[-2].byteLength != 32 || pk[-3].byteLength != 32) {
                throw new Error("pubkey EC coords have bad length")
        }
+}
+
+function reformatPubkey(pk, rpid) {
+       checkPubkey(pk)
        let msg = new SSHMSG()
        msg.putString("sk-ecdsa-sha2-nistp256@openssh.com")     // Key type
        msg.putString("nistp256")                               // Key curve
@@ -479,6 +516,43 @@ function reformatPubkey(pk, rpid) {
        return msg.serialise()
 }
 
+function reformatPrivkey(pk, rpid, kh, flags) {
+       checkPubkey(pk)
+       let msg = new SSHMSG()
+       msg.putString("sk-ecdsa-sha2-nistp256@openssh.com")     // Key type
+       msg.putString("nistp256")                               // Key curve
+       msg.putECPoint(pk[-2], pk[-3])                          // EC key
+       msg.putString(rpid)                                     // RP ID
+       msg.putU8(flags)                                        // flags
+       msg.putBytes(kh)                                        // handle
+       msg.putString("")                                       // reserved
+       return msg.serialise()
+}
+
+function privkeyFile(pub, priv, user, rp) {
+       let innerMsg = new SSHMSG()
+       innerMsg.putU32(0xdeadbeef)                             // check byte
+       innerMsg.putU32(0xdeadbeef)                             // check byte
+       innerMsg.put(priv)                                      // privkey
+       innerMsg.putString("webauthn.html " + user + "@" + rp)  // comment
+       // Pad to cipher blocksize (8).
+       p = 1
+       while (innerMsg.length() % 8 != 0) {
+               innerMsg.putU8(p++)
+       }
+       let msg = new SSHMSG()
+       msg.putStringRaw("openssh-key-v1")                      // Magic
+       msg.putU8(0)                                            // \0 terminate
+       msg.putString("none")                                   // cipher
+       msg.putString("none")                                   // KDF
+       msg.putString("")                                       // KDF options
+       msg.putU32(1)                                           // nkeys
+       msg.putBytes(pub)                                       // pubkey
+       msg.putSSHMSG(innerMsg)                                 // inner
+       //msg.put(innerMsg.serialise())                         // inner
+       return msg.serialise()
+}
+
 async function assertform_submit(event) {
        event.preventDefault();
        console.log("submitted")