SOPS: Secrets OPerationS ======================== **sop** is an editor of encrypted files that supports YAML, JSON and TEXT formats and encrypts with AWS KMS and PGP (via GnuPG). Watch `the demo `_. .. image:: http://i.imgur.com/IL6dlhm.gif .. image:: https://travis-ci.org/mozilla/sops.svg?branch=master :target: https://travis-ci.org/mozilla/sops .. sectnum:: .. contents:: Table of Contents Up and running in 60 seconds ---------------------------- First install some libraries from your package manager: * RHEL family:: sudo yum install libyaml-devel python-devel libffi-devel pip * Debian family:: sudo apt-get install libyaml-dev python-dev libffi-dev python-pip * MacOS:: brew install libffi libyaml sudo easy_install pip Then install `sops` from pip:: sudo pip install --upgrade sops Clone the repository, load the test PGP key and open the test files:: $ git clone https://github.com/mozilla/sops.git $ cd sops $ gpg --import tests/sops_functional_tests_key.asc $ sops example.yaml This last step will decrypt `example.yaml` using the test private key. To create your own secrets files using keys under your control, keep reading. Usage ----- If you're using AWS KMS, create one or multiple master keys in the IAM console and export them, comma separated, in the **SOPS_KMS_ARN** env variable. It is recommended to use at least two master keys in different regions. .. code:: bash export SOPS_KMS_ARN="arn:aws:kms:us-east-1:656532927350:key/920aff2e-c5f1-4040-943a-047fa387b27e,arn:aws:kms:ap-southeast-1:656532927350:key/9006a8aa-0fa6-4c14-930e-a2dfb916de1d" Your AWS credentials must be present in `~/.aws/credentials`. sops uses boto3. .. code:: $ cat ~/.aws/credentials [default] aws_access_key_id = AKI..... aws_secret_access_key = mw...... If you want to use PGP, export the fingerprints of the public keys, comma separated, in the **SOPS_PGP_FP** env variable. .. code:: bash export SOPS_PGP_FP="85D77543B3D624B63CEA9E6DBC17301B491B3F21,E60892BB9BD89A69F759A1A0A3D652173B763E8F" Note: you can use both PGP and KMS simultaneously. Then simply call `sops` with a file path as argument. It will handle the encryption/decryption transparently and open the cleartext file in an editor. .. code:: bash $ sops mynewtestfile.yaml mynewtestfile.yaml doesn't exist, creating it. please wait while an encryption key is being generated and stored in a secure fashion [... editing happens in vim, or whatever $EDITOR is set to ...] file written to mynewtestfile.yaml The resulting encrypted file looks like this: .. code:: yaml myapp1: ENC[AES256_GCM,data:Tr7o=,iv:1=,aad:No=,tag:k=] app2: db: user: ENC[AES256_GCM,data:CwE4O1s=,iv:2k=,aad:o=,tag:w==] password: ENC[AES256_GCM,data:p673w==,iv:YY=,aad:UQ=,tag:A=] # private key for secret operations in app2 key: |- ENC[AES256_GCM,data:Ea3kL5O5U8=,iv:DM=,aad:FKA=,tag:EA==] an_array: - ENC[AES256_GCM,data:v8jQ=,iv:HBE=,aad:21c=,tag:gA==] - ENC[AES256_GCM,data:X10=,iv:o8=,aad:CQ=,tag:Hw==] - ENC[AES256_GCM,data:KN=,iv:160=,aad:fI4=,tag:tNw==] sops: kms: - created_at: 1441570389.775376 enc: CiC....Pm1Hm arn: arn:aws:kms:us-east-1:656532927350:key/920aff2e-c5f1-4040-943a-047fa387b27e - created_at: 1441570391.925734 enc: Ci...awNx arn: arn:aws:kms:ap-southeast-1:656532927350:key/9006a8aa-0fa6-4c14-930e-a2dfb916de1d pgp: - fp: 85D77543B3D624B63CEA9E6DBC17301B491B3F21 created_at: 1441570391.930042 enc: | -----BEGIN PGP MESSAGE----- hQIMA0t4uZHfl9qgAQ//UvGAwGePyHuf2/zayWcloGaDs0MzI+zw6CmXvMRNPUsA ...=oJgS -----END PGP MESSAGE----- A copy of the encryption/decryption key is stored securely in each KMS and PGP block. As long as one of the KMS or PGP method is still usable, you will be able to access you data. To decrypt a file in a `cat` fashion, use the `-d` flag: .. code:: bash $ sops -d mynewtestfile.yaml `sops` encrypted files contain the necessary information to decrypt their content. All a user of `sops` need is valid AWS credentials and the necessary permissions on KMS keys. Given that, the only command a `sops` user need is: .. code:: bash $ sops `` will be opened, decrypted, passed to a text editor (vim by default), encrypted if modified, and saved back to its original location. All of these steps, apart from the actual editing, are transparent to the user. Adding and removing keys ~~~~~~~~~~~~~~~~~~~~~~~~ When creating a new files, `sops` uses the PGP and KMS defined in the command line arguments `--kms` and `--pgp`, or from the environment variables `SOPS_KMS_ARN` and `SOPS_PGP_FP`. That information is stored in the file under the `sops` section. When editing a file, it is trivial to add or remove keys: invoke `sops` with the flag **-s** to display the master keys while editing, and add or remove kms or pgp keys under the sops section. For example, to add a KMS master key to a file, we would add the following entry: .. code:: yaml sops: kms: - arn: arn:aws:kms:us-east-1:656532927350:key/920aff2e-c5f1-4040-943a-047fa387b27e And, similarly, to add a PGP master key, we add its fingerprint: .. code:: yaml sops: pgp: - fp: 85D77543B3D624B63CEA9E6DBC17301B491B3F21 When the file is saved, `sops` will update its metadata and encrypt the data key with the freshly added master keys. The removed entries are simply deleted from the file. Using KMS master keys in various AWS accounts ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can use keys in various accounts by tying each KMS master key to a role that the user is allowed to assume in each account. The `IAM roles `_ documentation has full details on how this needs to be configured on AWS's side. From the point of view of `sops`, you only need to specify the role a KMS key must assume alongside its ARN, as follows: .. code:: yaml sops: kms: - arn: arn:aws:kms:us-east-1:656532927350:key/920aff2e-c5f1-4040-943a-047fa387b27e role: arn:aws:iam::927034868273:role/sops-dev-xyz The role must have permission to call Encrypt and Decrypt using KMS. An example policy is shown below. .. code:: json { "Sid": "Allow use of the key", "Effect": "Allow", "Action": [ "kms:Encrypt", "kms:Decrypt", "kms:ReEncrypt*", "kms:GenerateDataKey*", "kms:DescribeKey" ], "Resource": "*", "Principal": { "AWS": [ "arn:aws:iam::927034868273:role/sops-dev-xyz" ] } } You can specify a role in the `--kms` flag and `SOPS_KMS_ARN` variable by appending it to the ARN of the master key, separated by a **+** sign:: + arn:aws:kms:us-west-2:927034868273:key/fe86dd69-4132-404c-ab86-4269956b4500+arn:aws:iam::927034868273:role/sops-dev-xyz Key Rotation ~~~~~~~~~~~~ It is recommend to renew the data key on a regular basis. `sops` supports key rotation via the `-r` flag. A simple approach is to decrypt and reencrypt all files in place with rotation enabled: .. code:: bash for file in $(find . -type f -name "*.yaml"); do sops -d -i $file sops -e -i -r $file done Examples -------- Creating a new file ~~~~~~~~~~~~~~~~~~~ The command below create a new file with a data key encrypted by KMS and PGP. .. code:: bash $ sops --kms "arn:aws:kms:us-west-2:927034868273:key/fe86dd69-4132-404c-ab86-4269956b4500" --pgp C9CAB0AF1165060DB58D6D6B2653B624D620786D /path/to/new/file.yaml Encrypting an existing file ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Similar to the previous command, we tell sops to use one KMS and one PGP key. The path points to an existing cleartext file, so we give sops flag `-e` to encrypt the file, and redirect the output to a destination file. .. code:: bash $ export SOPS_KMS+ARN="arn:aws:kms:us-west-2:927034868273:key/fe86dd69-4132-404c-ab86-4269956b4500" $ export SOPS_PGP_FP="C9CAB0AF1165060DB58D6D6B2653B624D620786D" $ sops -e /path/to/existing/file.yaml > /path/to/new/encrypted/file.yaml Decrypt the file with `-d`. .. code:: bash $ sops -d /path/to/new/encrypted/file.yaml Encrypt or decrypt a file in place ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Rather than redirecting the output of `-e` or `-d`, sops can replace the original file after encrypting or decrypting it. .. code:: bash # file.yaml is in cleartext $ sops -e -i /path/to/existing/file.yaml # file.yaml is now encrypted $ sops -d -i /path/to/existing/file.yaml # file.yaml is back in cleartext Encrypting binary files ~~~~~~~~~~~~~~~~~~~~~~~ `sops` primary use case is encrypting YAML and JSON configuration files, but it also has the ability to manage binary files. When encrypting a binary, sops will read the data as bytes, encrypt it, store the encrypted base64 under `tree['data']` and write the result as JSON. Note that the base64 encoding of encrypted data can actually make the encrypted file larger than the cleartext one. In-place encryption/decryption also works on binary files. .. code:: $ dd if=/dev/urandom of=/tmp/somerandom bs=1024 count=512 512+0 records in 512+0 records out 524288 bytes (524 kB) copied, 0.0466158 s, 11.2 MB/s $ sha512sum /tmp/somerandom 9589bb20280e9d381f7a192000498c994e921b3cdb11d2ef5a986578dc2239a340b25ef30691bac72bdb14028270828dad7e8bd31e274af9828c40d216e60cbe /tmp/somerandom $ sops -e -i /tmp/somerandom please wait while a data encryption key is being generated and stored securely $ sops -d -i /tmp/somerandom $ sha512sum /tmp/somerandom 9589bb20280e9d381f7a192000498c994e921b3cdb11d2ef5a986578dc2239a340b25ef30691bac72bdb14028270828dad7e8bd31e274af9828c40d216e60cbe /tmp/somerandom Extract a sub-part of a document tree ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ `sops` can extract a specific part of a YAML or JSON document, by provided the path in the `--extract` command line flag. This is useful to extract specific values, like keys, without needed an extra parser. .. code:: bash $ sops -d ~/git/svc/sops/example.yaml -t '["app2"]["key"]' -----BEGIN RSA PRIVATE KEY----- MIIBPAIBAAJBAPTMNIyHuZtpLYc7VsHQtwOkWYobkUblmHWRmbXzlAX6K8tMf3Wf ImcbNkqAKnELzFAPSBeEMhrBN0PyOC9lYlMCAwEAAQJBALXD4sjuBn1E7Y9aGiMz bJEBuZJ4wbhYxomVoQKfaCu+kH80uLFZKoSz85/ySauWE8LgZcMLIBoiXNhDKfQL vHECIQD6tCG9NMFWor69kgbX8vK5Y+QL+kRq+9HK6yZ9a+hsLQIhAPn4Ie6HGTjw fHSTXWZpGSan7NwTkIu4U5q2SlLjcZh/AiEA78NYRRBwGwAYNUqzutGBqyXKUl4u Erb0xAEyVV7e8J0CIQC8VBY8f8yg+Y7Kxbw4zDYGyb3KkXL10YorpeuZR4LuQQIg bKGPkMM4w5blyE1tqGN0T7sJwEx+EUOgacRNqM2ljVA= -----END RSA PRIVATE KEY----- The tree path syntax uses a regular python dictionary syntax, without the variable name. Extract keys by naming them, and array elements by numbering them. .. code:: bash $ sops -d ~/git/svc/sops/example.yaml -t '["an_array"][1]' secretuser2 Using sops as a library in a python script ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can import sops as a module and use it in your python program. .. code:: python import sops pathtype = sops.detect_filetype(path) tree = sops.load_file_into_tree(path, pathtype) sops_key, tree = sops.get_key(tree) tree = sops.walk_and_decrypt(tree, sops_key) sops.write_file(tree, path=path, filetype=pathtype) YAML types limitations ---------------------- `sops` only supports a subset of `YAML`'s many types. Encrypting YAML files that contain strings, numbers and booleans will work fine. Files that contain anchors will not work, because the anchors redefine that structure of the file at load time. `sops` uses the path to a value as additional data in the AEAD encryption, and thus dynamic paths generated by anchors break the authentication step. JSON and TEXT file types have no such feature and do not suffer this limitation. Cryptographic details --------------------- When sops creates a file, it generates a random 256 bits data key and asks each KMS and PGP master key to encrypt the data key. The encrypted version of the data key is stored in the `sops` metadata under `sops.kms` and `sops.pgp`. For KMS: .. code:: yaml sops: kms: - enc: CiC6yCOtzsnFhkfdIslYZ0bAf//gYLYCmIu87B3sy/5yYxKnAQEBAQB4usgjrc7JxYZH3SLJWGdGwH//4GC2ApiLvOwd7Mv+cmMAAAB+MHwGCSqGSIb3DQEHBqBvMG0CAQAwaAYJKoZIhvcNAQcBMB4GCWCGSAFlAwQBLjARBAyGdRODuYMHbA8Ozj8CARCAO7opMolPJUmBXd39Zlp0L2H9fzMKidHm1vvaF6nNFq0ClRY7FlIZmTm4JfnOebPseffiXFn9tG8cq7oi enc_ts: 1439568549.245995 arn: arn:aws:kms:us-east-1:656532927350:key/920aff2e-c5f1-4040-943a-047fa387b27e For PGP: .. code:: yaml sops: pgp: - fp: 85D77543B3D624B63CEA9E6DBC17301B491B3F21 created_at: 1441570391.930042 enc: | -----BEGIN PGP MESSAGE----- Version: GnuPG v1 hQIMA0t4uZHfl9qgAQ//UvGAwGePyHuf2/zayWcloGaDs0MzI+zw6CmXvMRNPUsA pAgRKczJmDu4+XzN+cxX5Iq9xEWIbny9B5rOjwTXT3qcUYZ4Gkzbq4MWkjuPp/Iv qO4MJaYzoH5YxC4YORQ2LvzhA2YGsCzYnljmatGEUNg01yJ6r5mwFwDxl4Nc80Cn RwnHuGExK8j1jYJZu/juK1qRbuBOAuruIPPWVdFB845PA7waacG1IdUW3ZtBkOy3 O0BIfG2ekRg0Nik6sTOhDUA+l2bewCcECI8FYCEjwHm9Sg5cxmP2V5m1mby+uKAm kewaoOyjbmV1Mh3iI1b/AQMr+/6ZE9MT2KnsoWosYamFyjxV5r1ZZM7cWKnOT+tu KOvGhTV1TeOfVpajNTNwtV/Oyh3mMLQ0F0HgCTqomQVqw5+sj7OWAASuD3CU/dyo pcmY5Qe0TNL1JsMNEH8LJDqSh+E0hsUxdY1ouVsg3ysf6mdM8ciWb3WRGxih1Vmf unfLy8Ly3V7ZIC8EHV8aLJqh32jIZV4i2zXIoO4ZBKrudKcECY1C2+zb/TziVAL8 qyPe47q8gi1rIyEv5uirLZjgpP+JkDUgoMnzlX334FZ9pWtQMYW4Y67urAI4xUq6 /q1zBAeHoeeeQK+YKDB7Ak/Y22YsiqQbNp2n4CKSKAE4erZLWVtDvSp+49SWmS/S XgGi+13MaXIp0ecPKyNTBjF+NOw/I3muyKr8EbDHrd2XgIT06QXqjYLsCb1TZ0zm xgXsOTY3b+ONQ2zjhcovanDp7/k77B+gFitLYKg4BLZsl7gJB12T8MQnpfSmRT4= =oJgS -----END PGP MESSAGE----- sops then opens a text editor on the newly created file. The user adds data to the file and saves it when done. Upon save, sops browses the entire file as of a key/value tree. Every time sops encounters a leaf value (a value that does not have children), it encrypts the value with AES256_GCM using the data key and a 256 bits random initialization vector. Each file uses a single data key to encrypt all values of a document, but each value receives a unique initialization vector and has unique authentication data. Additional data is used to guarantee the integrity of the encrypted data and of the tree structure: when encrypting the tree, key names are concatenated into a byte string that is used as AEAD additional data (aad) when encrypting the value. The `aad` field is not stored with the value but reconstructed from the tree structure every time, thus guaranteeing the integrity of the file structure. For example, the following YAML document: .. code:: yaml path: to: my: information: - value1 - value2 will be encrypted with AAD `path:to:my:information:` and verified at decryption. The result of AES256_GCM encryption is stored in the leaf of the tree using a base64 encoded string format:: ENC[AES256_GCM, data:CwE4O1s=, iv:S0fozGAOxNma/pWDUuk1iEaYw0wlba0VOLHjPxIok2k=, tag:XaGsYaL9LCkLWJI0uxnTYw==] where: * **data** is the encrypted value * **iv** is the 256 bits initialization vector * **tag** is the authentication tag The encrypted file is written to disk with nested keys in cleartext and values encrypted. We expect that keys do not carry sensitive information, and keeping them in cleartext allows for better diff and overall readability. Any valid KMS or PGP master key can later decrypt the data key and access the data. Multiple master keys allow for sharing encrypted files without sharing master keys, and provide disaster recovery solution. The recommended way to use sops is to have two KMS master keys in different region and one PGP public key with the private key stored offline. If, by any chance, both KMS master keys are lost, you can always recover the encrypted data using the PGP private key. Message Authentication Code ~~~~~~~~~~~~~~~~~~~~~~~~~~~ In addition to authenticating branches of the tree using keys as additional data, sops computes a MAC on all the values to ensure that no value has been added or removed fraudulently. The MAC is stored encrypted with AES_GCM and the data key under tree->`sops`->`mac`. Threat Model ------------ The security of the data stored using sops is as strong as the weakest cryptographic mechanism. Values are encrypted using AES256_GCM which is the strongest symetric encryption algorithm known today. Data keys are encrypted in either KMS, which also uses AES256_GCM, or PGP which uses either RSA or ECDSA keys. Going from the most likely to the least likely, the threats are as follow: 1. Compromised AWS credentials grant access to KMS master key ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ An attacker with access to an AWS console can grant itself access to one of the KMS master key used to encrypt a sops data key. This threat should be mitigated by protecting AWS accesses with strong controls, such as multi-factor authentication, and also by performing regular audits of permissions granted to AWS users. 2. Compromised PGP key ~~~~~~~~~~~~~~~~~~~~~~ PGP keys are routinely mishandled, either because owners copy them from machine to machine, or because the key is left forgotten on an unused machine an attacker gains access to. When using PGP encryption, sops users should take special care of PGP private keys, and store them on smart cards or offline as often as possible. 3. Factorized RSA key ~~~~~~~~~~~~~~~~~~~~~ sops doesn't apply any restriction on the size or type of PGP keys. A weak PGP keys, for example 512 bits RSA, could be factorized by an attacker to gain access to the private key and decrypt the data key. Users of sops should rely on strong keys, such as 2048+ bits RSA keys, or 256+ bits ECDSA keys. 4. Weak AES cryptography ~~~~~~~~~~~~~~~~~~~~~~~~ A vulnerability in AES256_GCM could potentially leak the data key or the KMS master key used by a sops encrypted file. While no such vulnerability exists today, we recommend that users keep their encrypted files reasonably private. License ------- Mozilla Public License Version 2.0 Authors ------- * Julien Vehent * Daniel Thornton * Alexis Metaireau * Rémy Hubscher Credits ------- `sops` is inspired by `hiera-eyaml `_, `credstash `_ , `sneaker `_, `password store `_ and too many years managing PGP encrypted files by hand...