diff --git a/.sig/manifest.8E47A1EC35A1551D.asc b/.sig/manifest.8E47A1EC35A1551D.asc
index 03423eb..83f0a30 100644
--- a/.sig/manifest.8E47A1EC35A1551D.asc
+++ b/.sig/manifest.8E47A1EC35A1551D.asc
@@ -1,16 +1,16 @@
 -----BEGIN PGP SIGNATURE-----
 
-iQIzBAABCgAdFiEEZ1U/vaRrtxq9LgsLjkeh7DWhVR0FAl+yZBsACgkQjkeh7DWh
-VR2DqA/9FIc1IgqyiwL3+kA5SnfHDC73WdKLP0g2SZbdwxhlW4ZZCgiEKBRcUZte
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-Bh+LBgH7NMpg4x8zkTFdZwsAYMCsiHzkFOisDG2IKjoq7NkAXGU=
-=0W8T
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+=opFX
 -----END PGP SIGNATURE-----
diff --git a/.sig/manifest.txt b/.sig/manifest.txt
index 0c7a6fd..ff048e9 100644
--- a/.sig/manifest.txt
+++ b/.sig/manifest.txt
@@ -1,2 +1,2 @@
 64263feac7b00952e9ec3b6c1fd11316faa58ff673c6bd085fac9f6f8d8389f6 .gitignore
-03bc3d3bbd3a4831a7d8b05c42fa1404c6672a15f7d749765a96bb725c1a4752 sig
+b470a31ed13fb1177a0ffae1872f3e24f9aa8292090f4d838ad2a4bc639f8404 sig
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..705178c
--- /dev/null
+++ b/README.md
@@ -0,0 +1,99 @@
+# Sig #
+
+The simple GPG signature toolchain for directories or git repos.
+
+## Features
+
+  * Generate sha256 manifest for all files in directory
+    * Use git for listing if available
+  * Add detached signatures to manifest
+  * Verify manifest has a minimum threshold of unique detached signatures
+  * Verify git history contains a minimum threshold of unique commit siguatures
+  * Verify signatures belong to a defined GPG alias group
+
+## Install
+
+  1. Clone
+    ```
+    git clone git@gitlab.com/pchq/sig.git sig
+    ```
+
+  2. Manually verify
+    ```
+    for file in .sig/*.asc; do gpg --verify $file .sig/manifest.txt; done
+    gpg log --show-signature
+    less sig
+    ```
+
+  3. Self verify
+    ```
+    ./sig verify --threshold 3
+    ```
+
+  4. Copy to $PATH
+    ```
+    cp sig ~/.local/bin/
+    ```
+
+## Methods
+
+### Git
+
+This method verifies a git repo contains signed commits by one or more authors.
+
+If 'threshold' is specified, it searches history until enough unique signatures
+are found to satisify the threshold, ensuring all commits between are signed.
+
+If 'group' is specified, all signatures must be by keys that belong to a
+defined gpg alias group.
+
+Note: this only proves the history had multiple participants, but not that
+the current HEAD was verified by all participants.
+
+#### Assumptions
+  - Single sig mode: Repo HEAD controlled by signer
+  - Multi-sig mode: Repo has contributions from multiple individuals
+  - Multi-sig group mode: Repo has contributions from specified individuals
+  - Sha1 is not broken
+
+### Detached
+
+This method verifies the state of this folder was signed exactly as-is by one
+or more authors.
+
+If 'threshold' is specified, then that number of signatures must be present.
+
+If 'group' is specified, all signatures must be by keys that belong to a
+defined gpg alias group.
+
+#### Assumptions
+  - Single sig mode: Folder contents controlled by signer
+  - Multi-sig mode: Folder contents verified by multiple signers
+  - Multi-sig group mode: Folder contents approved by specified individuals
+  - Sha256 is not broken
+
+## Usage
+
+### Verify 1 signature via Detached and Git methods
+
+```
+sig verify
+```
+
+### Verify 2 unique signatures via Detached and Git methods
+
+```
+sig verify --threshold 2
+```
+
+### Verify 3 unique signatures from specified signing group via Git method
+
+```
+sig verify --threshold 2 --group myteam --method git
+```
+
+### Add Detached Signature
+
+```
+sig add
+```
diff --git a/sig b/sig
index 44a9373..a2abdcb 100755
--- a/sig
+++ b/sig
@@ -110,6 +110,7 @@ get_files(){
 	fi
 }
 
+### Get signer name/email from key fingerprint
 get_signer(){
 	local fingerprint="${1?}"
 	gpg \
@@ -177,6 +178,7 @@ verify_git(){
 	local sig_count=0
 	local seen_fingerprints=""
 	local depth=0
+	#TODO: implement group validation
 
 	while [[ $depth != "$(git rev-list --count HEAD)" ]]; do
 		ref=HEAD~${depth}