Amber/VERIFY_RELEASES.md

Verifying Amber Releases

Overview

All Amber releases are cryptographically signed using GPG to ensure integrity and authenticity. This guide explains how to verify that the releases you download are genuine and haven't been tampered with.

Prerequisites

You'll need to have gpg or gpg2 installed on your system:

• Ubuntu/Debian: sudo apt install gnupg
• macOS: brew install gnupg
• Windows: Install Gpg4win

Step 1: Import the Signing Key

First, import the GPG key used to sign Amber releases:

gpg --keyserver hkps://keys.openpgp.org --recv-keys 44F0AAEB77F373747E3D5444885822EED3A26A6D

You should see output similar to:

gpg: key EE1FA70568414E2A: public key "greenart7c3 <greenart7c3@proton.me>" imported
gpg: Total number processed: 1
gpg:               imported: 1

Step 2: Verify the Key Fingerprint

IMPORTANT: Always verify the key fingerprint matches exactly:

gpg --fingerprint 44F0AAEB77F373747E3D5444885822EED3A26A6D

The output should show:

pub   rsa3072 2025-09-04 [SC]
      44F0 AAEB 77F3 7374 7E3D  5444 8858 22EE D3A2 6A6D
uid           [unknown] greenart7c3 <greenart7c3@proton.me>
sub   rsa3072 2025-09-04 [E]

Verify the fingerprint: 44F0 AAEB 77F3 7374 7E3D 5444 8858 22EE D3A2 6A6D

If the fingerprint doesn't match exactly, DO NOT PROCEED - the key may be compromised.

Step 3: Download Release Files

For each release, you need to download:

1. The APK/AAB files you want to use
2. The manifest file (e.g., manifest-v1.0.0.txt)
3. The signature file (e.g., manifest-v1.0.0.txt.sig)

Example for version v1.0.0:

# Download the files you need
wget https://github.com/yourusername/Amber/releases/download/v1.0.0/amber-free-universal-v1.0.0.apk
wget https://github.com/yourusername/Amber/releases/download/v1.0.0/manifest-v1.0.0.txt
wget https://github.com/yourusername/Amber/releases/download/v1.0.0/manifest-v1.0.0.txt.sig

Step 4: Verify the Manifest Signature

Verify that the manifest file is authentic:

gpg --verify manifest-v1.0.0.txt.sig manifest-v1.0.0.txt

You should see output like:

gpg: Signature made Wed 04 Sep 2025 12:00:00 PM UTC
gpg:                using RSA key 44F0AAEB77F373747E3D5444885822EED3A26A6D
gpg: Good signature from "greenart7c3 <greenart7c3@proton.me>"
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 44F0 AAEB 77F3 7374 7E3D  5444 8858 22EE D3A2 6A6D

The "Good signature" message is what you're looking for. The warning about the key not being certified is normal unless you've explicitly trusted the key.

Step 5: Verify File Integrity

Check that your downloaded files match the checksums in the manifest:

# View the manifest contents
cat manifest-v1.0.0.txt

# Check the SHA256 hash of your downloaded file
sha256sum amber-free-universal-v1.0.0.apk

Compare the output hash with the corresponding hash in the manifest file. They must match exactly.

Automated Verification Script

You can use this script to automate the verification process:

#!/bin/bash
# verify-amber.sh

VERSION=${1:-"v1.0.0"}
FILE=${2:-"amber-free-universal-${VERSION}.apk"}

echo "Verifying Amber release ${VERSION}..."

# Download manifest and signature if not present
if [ ! -f "manifest-${VERSION}.txt" ]; then
    wget "https://github.com/yourusername/Amber/releases/download/${VERSION}/manifest-${VERSION}.txt"
fi

if [ ! -f "manifest-${VERSION}.txt.sig" ]; then
    wget "https://github.com/yourusername/Amber/releases/download/${VERSION}/manifest-${VERSION}.txt.sig"
fi

# Verify signature
echo "Verifying GPG signature..."
if gpg --verify "manifest-${VERSION}.txt.sig" "manifest-${VERSION}.txt"; then
    echo "✓ GPG signature is valid"
else
    echo "✗ GPG signature verification failed!"
    exit 1
fi

# Verify file hash if file exists
if [ -f "$FILE" ]; then
    echo "Verifying file integrity..."
    EXPECTED_HASH=$(grep "$FILE" "manifest-${VERSION}.txt" | cut -d' ' -f1)
    ACTUAL_HASH=$(sha256sum "$FILE" | cut -d' ' -f1)

    if [ "$EXPECTED_HASH" = "$ACTUAL_HASH" ]; then
        echo "✓ File integrity verified: $FILE"
    else
        echo "✗ File integrity check failed for: $FILE"
        echo "Expected: $EXPECTED_HASH"
        echo "Actual:   $ACTUAL_HASH"
        exit 1
    fi
else
    echo "File $FILE not found - please download it first"
fi

echo "✓ All verification checks passed!"

Make it executable and use it:

chmod +x verify-amber.sh
./verify-amber.sh v1.0.0 amber-free-universal-v1.0.0.apk

Trusting the Key (Optional)

If you want to suppress the "key not certified" warning and you've verified the key fingerprint through a trusted channel, you can sign the key locally:

gpg --sign-key 44F0AAEB77F373747E3D5444885822EED3A26A6D

Security Notes

• Always verify the key fingerprint before trusting any signatures
• Only download releases from the official GitHub repository
• Verify both the GPG signature AND the file hashes
• Keep your GPG software up to date
• If verification fails at any step, do not use the file and report it as a potential security issue

Troubleshooting

"gpg: Can't check signature: No public key"

You need to import the signing key first (see Step 1).

"gpg: BAD signature"

The file has been tampered with or corrupted. Do not use it.

Hash mismatch

The downloaded file doesn't match the expected checksum. Re-download the file or try a different mirror.

For more help, please open an issue on the GitHub repository.