Replace AWS Access Keys with Short-Lived Credentials

Configure AWS IAM to trust Vouch as an OIDC identity provider

Vouch eliminates static AWS access keys. You configure AWS to trust Vouch as an OIDC identity provider, and developers get temporary STS credentials – valid for up to 1 hour – after authenticating with their YubiKey. Every API call is tied to a verified human identity in CloudTrail.

How Vouch compares to aws login and aws sso login

AWS provides two built-in CLI authentication commands. Here is how they compare to Vouch:

• aws login – New in AWS CLI v2.32+. Opens a browser to authenticate with your AWS Console credentials (IAM user, root, or federated identity) and issues temporary credentials for up to 12 hours. It requires the SignInLocalDevelopmentAccess managed policy and only covers AWS – it does not provide credentials for SSH, GitHub, Docker registries, or other services.

• aws sso login – Authenticates through AWS IAM Identity Center (formerly AWS SSO). It requires an Identity Center instance and an SSO-configured profile (aws configure sso). Like aws login, it only covers AWS services.

• vouch login – Authenticates with a FIDO2 hardware key (YubiKey) and provides credentials for AWS, SSH, GitHub, Docker registries, Cargo registries, AWS CodeCommit, AWS CodeArtifact, databases, and any OIDC-compatible application – all from a single session. Every credential is tied to a hardware-verified human identity, and authentication is phishing-resistant by design.

If you already use IAM Identity Center, aws sso login may cover your AWS needs. Vouch is a better fit when you want a single authentication event to cover AWS and everything else your team uses, with the guarantee that every credential traces back to a physical hardware key.

How it works

1. The developer runs vouch login and authenticates with their YubiKey.
2. The Vouch server issues a short-lived OIDC ID token signed with ES256 (ECDSA over P-256). The user’s identity is carried in the sub claim (the developer’s email address), which AWS exposes as ${<instance>:sub} in IAM trust policies.
3. When the developer runs an AWS command (or vouch credential aws), the CLI calls AWS STS AssumeRoleWithWebIdentity, presenting the ID token.
4. AWS validates the token signature against the Vouch server’s JWKS endpoint, checks the audience and issuer, and returns temporary credentials (access key, secret key, session token) valid for up to 1 hour.
5. The developer’s AWS CLI, SDK, or Terraform session uses these credentials transparently.

Because the ID token is scoped to the authenticated user and is short-lived, credentials cannot be shared or reused after expiry.

Step 1 – Choose your topology

Admin task

Vouch uses exactly one OIDC provider per organization. Where it lives depends on your AWS layout:

We don’t recommend deploying multiple OIDC providers across independent accounts. In practice, you either have one account or you have an Organization, and the Organization case is best served by chaining through a single hub.

Step 2 – Register the Vouch OIDC provider

Admin task

Before any user can assume a role, an administrator must register the Vouch server as an OIDC identity provider. Run this once in the AWS account you chose in Step 1 (single account, or the management account of an Organization).

AWS CLI

For background on OIDC identity providers in AWS, see Creating OpenID Connect (OIDC) identity providers in the AWS documentation.

aws iam create-open-id-connect-provider \
  --url "https://us.vouch.sh" \
  --client-id-list "https://us.vouch.sh"

Note: AWS fetches the JWKS from https://us.vouch.sh/.well-known/jwks.json at runtime to verify token signatures. A ThumbprintList is no longer required – AWS obtains the root CA thumbprint automatically.

CloudFormation

AWSTemplateFormatVersion: "2010-09-09"
Description: Vouch OIDC Identity Provider

Resources:
  VouchOIDCProvider:
    Type: "AWS::IAM::OIDCProvider"
    Properties:
      Url: "https://us.vouch.sh"
      ClientIdList:
        - "https://us.vouch.sh"

Terraform

resource "aws_iam_openid_connect_provider" "vouch" {
  url            = "https://us.vouch.sh"
  client_id_list = ["https://us.vouch.sh"]
}

Step 3 – Deploy a Vouch role

Admin task

The role you deploy here is the entry point for vouch login – the role developers federate into directly from their YubiKey-backed session. Its trust policy is the same regardless of what the role is allowed to do; only the identity policy changes based on how you want to use it. Pick one of three patterns:

• Pattern A – Managed policy – Attach an AWS-managed policy like PowerUserAccess or ReadOnlyAccess. Best for getting started.
• Pattern B – Explicit actions – Attach a custom least-privilege policy listing specific actions. Best when you know what your team needs.
• Pattern C – sts:AssumeRole only – The role can do nothing in this account except assume roles in other accounts. This is the management-account hub for an AWS Organization; spoke roles in member accounts use a different trust policy and are covered in Multi-Account AWS.

All three patterns share the trust policy below. The *@example.com condition limits role assumption to anyone with a verified email in your domain (see Tips for restricting access for narrower patterns).

Shared trust policy

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Federated": "arn:aws:iam::ACCOUNT_ID:oidc-provider/us.vouch.sh"
      },
      "Action": [
        "sts:AssumeRoleWithWebIdentity",
        "sts:SetSourceIdentity",
        "sts:TagSession"
      ],
      "Condition": {
        "StringEquals": {
          "us.vouch.sh:aud": "https://us.vouch.sh"
        },
        "StringLike": {
          "us.vouch.sh:sub": "*@example.com",
          "sts:RoleSessionName": "${us.vouch.sh:sub}"
        }
      }
    }
  ]
}

Pattern A – Managed policy

Attach an AWS-managed policy. This is the fastest way to get a working role.

CloudFormation

Resources:
  VouchDeveloperRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: VouchDeveloper
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Federated: !Sub "arn:${AWS::Partition}:iam::${AWS::AccountId}:oidc-provider/us.vouch.sh"
            Action:
              - "sts:AssumeRoleWithWebIdentity"
              - "sts:SetSourceIdentity"
              - "sts:TagSession"
            Condition:
              StringEquals:
                "us.vouch.sh:aud": "https://us.vouch.sh"
              StringLike:
                "us.vouch.sh:sub": "*@example.com"
                "sts:RoleSessionName": "${us.vouch.sh:sub}"
      ManagedPolicyArns:
        - !Sub "arn:${AWS::Partition}:iam::aws:policy/PowerUserAccess"

Terraform

data "aws_caller_identity" "current" {}
data "aws_partition" "current" {}

locals {
  aws_partition  = data.aws_partition.current.partition
  aws_account_id = data.aws_caller_identity.current.account_id
}

resource "aws_iam_role" "vouch_developer" {
  name = "VouchDeveloper"

  assume_role_policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Effect = "Allow"
        Principal = {
          Federated = "arn:${local.aws_partition}:iam::${local.aws_account_id}:oidc-provider/us.vouch.sh"
        }
        Action = [
          "sts:AssumeRoleWithWebIdentity",
          "sts:SetSourceIdentity",
          "sts:TagSession",
        ]
        Condition = {
          StringEquals = {
            "us.vouch.sh:aud" = "https://us.vouch.sh"
          }
          StringLike = {
            "us.vouch.sh:sub" = "*@example.com"
            "sts:RoleSessionName"      = "${us.vouch.sh:sub}"
          }
        }
      }
    ]
  })

  managed_policy_arns = ["arn:${local.aws_partition}:iam::aws:policy/PowerUserAccess"]
}

Pattern B – Explicit actions

Attach a custom inline policy listing only the actions your team needs. Use the same trust policy and role definition as Pattern A; replace the ManagedPolicyArns block with an inline policy. Example – read/write a specific S3 bucket and read CloudWatch logs:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "s3:GetObject",
        "s3:PutObject",
        "s3:ListBucket"
      ],
      "Resource": [
        "arn:aws:s3:::my-app-data",
        "arn:aws:s3:::my-app-data/*"
      ]
    },
    {
      "Effect": "Allow",
      "Action": [
        "logs:GetLogEvents",
        "logs:FilterLogEvents",
        "logs:DescribeLogGroups",
        "logs:DescribeLogStreams"
      ],
      "Resource": "*"
    }
  ]
}

In CloudFormation, use Policies on the role; in Terraform, use aws_iam_role_policy.

Pattern C – sts:AssumeRole only

Use this pattern when the role is the management-account hub for an AWS Organization. The role itself can do nothing in this account except assume roles in member accounts.

Use the same shared trust policy as Pattern A (with *@example.com matching your domain). Replace the identity policy with:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "sts:AssumeRole",
        "sts:SetSourceIdentity",
        "sts:TagSession"
      ],
      "Resource": "arn:aws:iam::*:role/vouch/VouchAccess",
      "Condition": {
        "StringEquals": {
          "aws:PrincipalOrgId": "o-xxxxxxxxx"
        }
      }
    }
  ]
}

The aws:PrincipalOrgId condition restricts the hub to assuming roles only inside your AWS Organization. Replace o-xxxxxxxxx with your organization ID.

Continue with Multi-Account AWS to deploy the spoke roles in member accounts and configure chaining.

Tips for restricting access

Restrict by email address

Limit role assumption to specific users by adding an email condition to the trust policy:

"Condition": {
  "StringEquals": {
    "us.vouch.sh:aud": "https://us.vouch.sh",
    "us.vouch.sh:sub": ["user@example.com"]
  },
  "StringLike": {
    "sts:RoleSessionName": "${us.vouch.sh:sub}"
  }
}

Restrict by email domain

Allow any user from a specific domain:

"Condition": {
  "StringEquals": {
    "us.vouch.sh:aud": "https://us.vouch.sh"
  },
  "StringLike": {
    "us.vouch.sh:sub": "*@example.com",
    "sts:RoleSessionName": "${us.vouch.sh:sub}"
  }
}

Revoke access for a specific user

There are two complementary techniques for cutting off a user. Use both together for full offboarding.

1. Immediate revocation via an explicit Deny on the role’s permissions policy. Permissions policies are evaluated on every AWS API call, and explicit Deny always wins. Because Vouch sets the vouch:Email session tag on every assumed-role session (see Session tags), you can block an offboarded user on the next API call – including calls made with STS credentials that the Vouch agent has already cached:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "DenyOffboardedUsers",
      "Effect": "Deny",
      "Action": "*",
      "Resource": "*",
      "Condition": {
        "StringEquals": {
          "aws:PrincipalTag/vouch:Email": [
            "former-employee@example.com"
          ]
        }
      }
    }
  ]
}

Attach this as an inline policy on each Vouch role, or apply it as a Service Control Policy in the management account to enforce it organization-wide. Because Vouch marks session tags as transitive, the vouch:Email tag propagates through role chains, so the same condition works in both the entry role and any spoke roles.

2. Block new role assumption via the trust policy. Add a StringNotEquals clause to the trust policy listing the emails to deny. The next AssumeRoleWithWebIdentity call from that user will fail:

"Condition": {
  "StringEquals": {
    "us.vouch.sh:aud": "https://us.vouch.sh"
  },
  "StringLike": {
    "us.vouch.sh:sub": "*@example.com",
    "sts:RoleSessionName": "${us.vouch.sh:sub}"
  },
  "StringNotEquals": {
    "us.vouch.sh:sub": ["former-employee@example.com"]
  }
}

On its own, this only takes effect when the Vouch agent’s cached STS credentials expire (up to 1 hour later), because the trust policy is evaluated at AssumeRoleWithWebIdentity time, not on every API call. Combined with the deny statement above, it provides a durable record of who is offboarded and prevents the role from being re-assumed even after the deny statement is later removed.

For full offboarding, also deactivate the user in Vouch so they cannot start new sessions and existing non-AWS credentials (like SSH certificates) are cut off:

• With SCIM provisioning, deactivating the user in your identity provider automatically revokes their active Vouch session and blocks future logins – no manual step required.
• Without SCIM, an administrator can use the Deactivate and Revoke credentials actions in the admin console to do the same thing.

Note that revoking the Vouch session does not invalidate STS credentials already cached in the user’s local Vouch agent – the explicit Deny from step 1 is what blocks those on the AWS side. The Vouch-side action prevents new sessions and severs other credentials issued from the same session.

Prevent session name spoofing

The RoleSessionName is a client-provided STS API parameter. Without a trust policy condition, someone with a valid Vouch JWT could set it to another user’s email, making CloudTrail session ARNs misleading. The sts:RoleSessionName condition binds the session name to the authenticated sub claim from the validated JWT:

"StringLike": {
  "sts:RoleSessionName": "${us.vouch.sh:sub}"
}

All trust policy examples in this guide include this condition. AWS rejects any AssumeRoleWithWebIdentity call where the session name does not match the OIDC subject.

Note: The immutable SourceIdentity claim (set to the user’s email) provides a second attribution anchor in CloudTrail that cannot be spoofed regardless of this condition.

Session tags

Vouch sets the following session tags when assuming a role, which you can use in IAM policies for attribute-based access control (ABAC):

You can reference these tags in IAM policy conditions using aws:PrincipalTag:

{
  "Condition": {
    "StringEquals": {
      "aws:PrincipalTag/vouch:Domain": "example.com"
    }
  }
}

Because Vouch marks all tags as transitive, they automatically propagate through role chains. If a developer assumes a hub role via Vouch and then chains into a spoke role in another account, the spoke role’s trust policy can still evaluate aws:PrincipalTag/vouch:Email and aws:PrincipalTag/vouch:Domain conditions.

Step 4 – Configure the Vouch CLI

Developer task

Each developer needs to tell the CLI which IAM role to assume and in which AWS profile to store the credentials. Run:

vouch setup aws --role arn:aws:iam::123456789012:role/VouchDeveloper

This command accepts the following flags:

• --role – The ARN of the IAM role created in Step 3 (required).
• --profile – The AWS profile name to write credentials to (default: vouch; additional profiles auto-name as vouch-2, vouch-3, etc.).

The command writes a credential_process entry into ~/.aws/config so that the AWS CLI and SDKs automatically call vouch credential aws whenever credentials are needed:

[profile vouch]
credential_process = vouch credential aws --role arn:aws:iam::123456789012:role/VouchDeveloper

Note: If you need a specific region for this profile, add a region line manually (e.g., region = us-east-1).

Step 5 – Test

Developer task

Verify that everything is working:

# Make sure you are logged in
vouch login

# Check your identity
aws sts get-caller-identity --profile vouch

Expected output:

{
  "UserId": "AROA...:alice@example.com",
  "Account": "123456789012",
  "Arn": "arn:aws:sts::123456789012:assumed-role/VouchDeveloper/alice@example.com"
}

Try running a command against a real AWS service:

aws s3 ls --profile vouch

Console access

Open the AWS Management Console directly from the CLI without entering credentials in a browser:

vouch aws console

This uses your active Vouch session to obtain temporary STS credentials, exchanges them for a federation sign-in token, and opens the console in your default browser. Pass --role to specify a role, or omit it to use the role from your configured AWS profile.

AI agent safety

When vouch credential aws runs inside an AI coding agent, Vouch automatically restricts the returned credentials to read-only access. No configuration is required – the CLI detects the agent environment and applies the restriction transparently.

How it works

The CLI checks for environment variables set by popular AI coding agents. When one is detected:

1. The ReadOnlyAccess AWS managed policy is attached as a session policy, which limits the effective permissions to the intersection of the role’s policies and ReadOnlyAccess – regardless of what the role itself allows.
2. The vouch:AccessType=ai and vouch:Agent=<name> session tags are added, where <name> is the verbatim value of the detected agent environment variable (for agents that set AI_AGENT or AGENT, the raw value is forwarded; for agents detected by a marker variable like CLAUDE_CODE or CURSOR_TRACE_ID, the agent name is used). These tags appear on every CloudTrail event for the session, so you can attribute API calls to the specific agent that made them.

Supported agents

Vouch detects the following AI coding agents:

If your agent is not listed, it will be detected if it sets the AGENT or AI_AGENT environment variable (an emerging convention).

Role chaining with agents

When using role chaining with an AI agent, Vouch applies an additional inline session policy to the management-account hop that restricts it to STS actions only (sts:AssumeRole, sts:TagSession, sts:SetSourceIdentity). The final role hop receives the ReadOnlyAccess session policy.

Troubleshooting

“Not authorized to perform sts:AssumeRoleWithWebIdentity”

• Verify the OIDC provider URL in the IAM trust policy matches https://us.vouch.sh exactly (no trailing slash).
• Confirm the aud condition matches the client ID registered with the OIDC provider.
• Ensure the trust policy Action includes all three required actions: sts:AssumeRoleWithWebIdentity, sts:SetSourceIdentity, and sts:TagSession.

“Token is expired”

• Run vouch login again to refresh your session. OIDC tokens are short-lived by design.

“Invalid identity token”

• Ensure the OIDC provider in AWS points to the correct Vouch server URL: https://us.vouch.sh.
• Verify that the Vouch server’s JWKS endpoint (https://us.vouch.sh/.well-known/jwks.json) is reachable from the internet (AWS must be able to fetch it).

Credentials not appearing in the expected profile

• Run vouch setup aws again and verify the profile name.
• Check ~/.aws/config for conflicting profile definitions.

Permission errors after assuming the role

• The trust policy controls who can assume the role; the permissions policy controls what they can do. Verify the correct permissions policies are attached to the IAM role.

Related guides

• Multi-Account AWS Strategy – Deploy Vouch across multiple AWS accounts with CloudFormation StackSets or Terraform modules.
• Amazon EKS – Use your Vouch-backed AWS credentials to authenticate to Kubernetes clusters.
• AWS Systems Manager – Connect to EC2 instances through Session Manager using Vouch credentials.
• Database Authentication – Connect to RDS, Aurora, and Redshift with IAM authentication.
• AWS CodeArtifact – Authenticate to package repositories using Vouch.
• Infrastructure as Code – Use CDK, Terraform, SAM, and other IaC tools with Vouch credentials.