forgejo-ssh-script/ideas_on_why_fail.md

Analysis of SSH Key Verification Failure

Observations from the Output

1. Key Generation

   • Successfully generated ED25519 key
   • Key fingerprint: SHA256:k4SR6Pnp3se+9CzgZjnHYS+FAP/gyNHnbRB8s/Z1KC8
   • Public key was generated and displayed correctly

2. Verification Attempts

   • Three attempts were made with different tokens
   • Each attempt followed the same process
   • All attempts failed with the same error
   • The signature format appears correct (has BEGIN/END markers)

3. Token Handling

   • Tokens were 64-character hex strings
   • Each attempt used a fresh token
   • Token format validation passed

4. Error Message Analysis

   • Forgejo reports: "The provided SSH key, signature or token do not match or token is out-of-date"
   • This suggests either:
     • The signature format is incorrect
     • The token has expired
     • There's a mismatch between the key and signature
     • The signature includes extra data

Potential Issues

1. Signature Generation

   • The echo -n command might not be working as expected in PowerShell
   • PowerShell's echo might be adding extra characters or line endings
   • The signature might include the "Signing data on standard input" line
   • The signature output might include debug/informational messages that should be filtered

2. Token Processing

   • The token might need to be processed differently (e.g., remove any whitespace)
   • The token might need to be in a specific format (uppercase/lowercase)
   • The token might need to be handled as raw bytes

3. SSH Key Format

   • The key might need to be in a specific format for Forgejo
   • The key comment might be affecting the verification
   • The key permissions might need to be set correctly

4. Forgejo Requirements

   • Forgejo might expect a specific signature format
   • The namespace (-n forgejo_token) might need to be different
   • The verification process might have changed in recent Forgejo versions

Prioritized Action Plan

1. Verify echo -n Behavior (HIGHEST PRIORITY)

# Test echo -n behavior in isolation
echo -n "test" | Format-Hex  # Check for any trailing newlines (0A)
# Expected output should show only the hex for "test" without 0A at the end

2. Refine Signature Output Filtering (HIGHEST PRIORITY)

# Test current output
$testToken = "a" * 64  # Create a dummy 64-char hex string
$testSignature = echo -n $testToken | ssh-keygen -Y sign -n forgejo_token -f "$privateKeyPath" 2>&1
$testSignature | Measure-Object -Character -Line  # Check character/line counts
$testSignature -match "Signing data on standard input"  # See if the phrase is there

# Implement filtering
$rawSignatureOutput = echo -n $Token | ssh-keygen -Y sign -n forgejo_token -f $privateKeyPath 2>&1
$verificationOutput = ($rawSignatureOutput | Where-Object { 
    $_ -match '^(-----BEGIN SSH SIGNATURE-----|-----END SSH SIGNATURE-----|[A-Za-z0-9+/=]+)$' 
} -join "`n").Trim()

# Verify filtered output
$verificationOutput | Format-Hex  # Check for any hidden characters

3. Manual Test Process (HIGH PRIORITY)

1. Get a fresh token from Forgejo
2. In a regular PowerShell window, run:

   echo -n <token> | ssh-keygen -Y sign -n forgejo_token -f ~/.ssh/id_ed25519
   

3. Copy the output manually and paste into Forgejo
4. If this works, the issue is in the script's output handling
5. Compare the manual signature with the script-generated one

4. Token Normalization (MEDIUM PRIORITY)

# Add to token processing
$token = $token.Trim().ToLower()  # Normalize token format
# Verify token format
$token | Format-Hex  # Check for any hidden characters

5. Key Comment Test (MEDIUM PRIORITY)

1. Generate a new key without the comment:

   ssh-keygen -t ed25519 -f $privateKeyPath  # Remove -C $email
   

2. Try the verification process with the new key

6. Alternative Token Passing Methods (LOW PRIORITY)

# Option 1: Using temporary file
"$Token" | Out-File -FilePath temp_token.txt -Encoding ascii -NoNewline
$signature = ssh-keygen -Y sign -n forgejo_token -f $privateKeyPath < temp_token.txt 2>&1
Remove-Item temp_token.txt

# Option 2: Using stdin stream
$stdin = New-Object System.IO.StringReader($Token)
$signature = ssh-keygen -Y sign -n forgejo_token -f $privateKeyPath -InputObject $stdin 2>&1

Questions to Consider

1. Does Forgejo provide any specific requirements for the signature format?
2. Are there any known issues with PowerShell's handling of binary data?
3. Should we try a different approach to passing the token to ssh-keygen?
4. Is there a way to verify the signature format before submitting it?
5. Could the key comment be causing issues with the verification?

Next Steps

1. Verify echo -n behavior in isolation
2. Implement the signature output filtering
3. Perform the manual test to verify the basic process
4. Add token normalization
5. Test without key comment
6. If needed, try alternative token passing methods

Debugging Tips

1. Use Measure-Object to check output lengths and line counts
2. Use Format-Hex to inspect for hidden characters
3. Compare manual vs. script-generated signatures
4. Check for any hidden characters in the output
5. Verify the exact format of the signature block
6. Monitor the token format throughout the process
7. Document the exact error message from Forgejo

Implementation Notes

1. Function Parameter Verification

   • Ensure Get-SshSignature receives correct $privateKeyPath
   • Add parameter validation in the function
   • Log the actual path being used

2. Output Inspection

   • Add debug logging for raw and filtered output
   • Compare lengths and formats at each step
   • Document any differences between manual and script output

3. Error Handling

   • Add specific error messages for each failure case
   • Log the exact format of the signature being sent
   • Document any differences from expected format