diff --git a/.github/workflows/ci_static-analysis.yaml b/.github/workflows/ci_static-analysis.yaml
index f06333e47..36aa1186f 100644
--- a/.github/workflows/ci_static-analysis.yaml
+++ b/.github/workflows/ci_static-analysis.yaml
@@ -11,5 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
+      - name: Upgrade setuptools
+        run: python -m pip install "setuptools<81"
       - name: not-grep
         uses: mattsb42-meta/not-grep@1.0.0
diff --git a/.github/workflows/shared-ci.yml b/.github/workflows/shared-ci.yml
index 74ef2c067..f4d2d315e 100644
--- a/.github/workflows/shared-ci.yml
+++ b/.github/workflows/shared-ci.yml
@@ -22,7 +22,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: ['18.x', '20.x', '22.x', 'latest']
+        node-version: ['22.x', 'latest']
         test-type: ['node', 'browser']
         # Determine test categories based on whether testing published packages or source code:
         # - Testing published packages: only run vector tests (don't have build artifacts to test coverage or compliance)
diff --git a/buildspec.yml b/buildspec.yml
index 3f8d21987..c4ce35eaf 100644
--- a/buildspec.yml
+++ b/buildspec.yml
@@ -3,22 +3,10 @@ version: 0.2
 batch:
   fast-fail: false
   build-list:
-    - identifier: testNodejs20
-      buildspec: codebuild/nodejs20.yml
-      env:
-        image: aws/codebuild/standard:5.0
-    - identifier: testNodejs18
-      buildspec: codebuild/nodejs18.yml
-      env:
-        image: aws/codebuild/standard:5.0
     - identifier: testNodejs16
       buildspec: codebuild/nodejs16.yml
       env:
         image: aws/codebuild/standard:5.0
-    - identifier: testBrowser18
-      buildspec: codebuild/browser18.yml
-      env:
-        image: aws/codebuild/standard:5.0
     - identifier: compliance
       buildspec: codebuild/compliance.yml
       env:
@@ -29,21 +17,3 @@ batch:
         variables:
           PUBLISH_LOCAL: "true"
         image: aws/codebuild/standard:5.0
-    - identifier: testVectorsNodejs18
-      buildspec: codebuild/test_vectors/nodejs18.yml
-      env:
-        variables:
-          PUBLISH_LOCAL: "true"
-        image: aws/codebuild/standard:5.0
-    - identifier: testVectorsNodejs20
-      buildspec: codebuild/test_vectors/nodejs20.yml
-      env:
-        variables:
-          PUBLISH_LOCAL: "true"
-        image: aws/codebuild/standard:5.0
-    - identifier: testVectorsBrowser18
-      buildspec: codebuild/test_vectors/browser18.yml
-      env:
-        variables:
-          PUBLISH_LOCAL: "true"
-        image: aws/codebuild/standard:5.0
diff --git a/codebuild/browser18.yml b/codebuild/browser18.yml
deleted file mode 100644
index 19a17bb0d..000000000
--- a/codebuild/browser18.yml
+++ /dev/null
@@ -1,17 +0,0 @@
-version: 0.2
-
-env:
-  variables:
-    NODE_OPTIONS: "--max-old-space-size=4096"
-
-phases:
-  install:
-    commands:
-      - n 18
-      - npm ci --unsafe-perm
-      - npm run build
-  build:
-    commands:
-      - npm -v
-      - node -v
-      - npm run coverage-browser
diff --git a/codebuild/nodejs18.yml b/codebuild/nodejs18.yml
deleted file mode 100644
index 6b43b4055..000000000
--- a/codebuild/nodejs18.yml
+++ /dev/null
@@ -1,19 +0,0 @@
-version: 0.2
-
-env:
-  variables:
-    NODE_OPTIONS: "--max-old-space-size=4096"
-
-phases:
-  install:
-    commands:
-      - n 18
-      - node -v
-      - npm -v
-      - npm ci --unsafe-perm
-      - npm run build
-  build:
-    commands:
-      - npm -v
-      - node -v
-      - npm run coverage-node
diff --git a/codebuild/nodejs20.yml b/codebuild/nodejs20.yml
deleted file mode 100644
index 76479dc0a..000000000
--- a/codebuild/nodejs20.yml
+++ /dev/null
@@ -1,23 +0,0 @@
-version: 0.2
-
-env:
-  variables:
-    NODE_OPTIONS: "--max-old-space-size=4096"
-
-phases:
-  install: 
-    commands:
-      - TMP_ROLE=$(aws sts assume-role --role-arn "arn:aws:iam::370957321024:role/GitHub-CI-MPL-Dafny-Role-us-west-2" --role-session-name "CB-TestVectorResources")
-      - export TMP_ROLE
-      - export AWS_ACCESS_KEY_ID=$(echo "${TMP_ROLE}" | jq -r '.Credentials.AccessKeyId')
-      - export AWS_SECRET_ACCESS_KEY=$(echo "${TMP_ROLE}" | jq -r '.Credentials.SecretAccessKey')
-      - export AWS_SESSION_TOKEN=$(echo "${TMP_ROLE}" | jq -r '.Credentials.SessionToken')
-      - aws sts get-caller-identity
-      
-      - n 20
-      - node --version ; npm --version
-      - npm ci --unsafe-perm
-      - npm run build
-  build:
-    commands:
-      - npm run coverage-node
diff --git a/codebuild/release/prod-release.yml b/codebuild/release/prod-release.yml
index 40f574929..e8e41c052 100644
--- a/codebuild/release/prod-release.yml
+++ b/codebuild/release/prod-release.yml
@@ -9,22 +9,14 @@ batch:
       buildspec: codebuild/compliance.yml
 
 # Unit Tests
-    - identifier: testNodejs20
-      buildspec: codebuild/nodejs20.yml
+    - identifier: testNodejs16
+      buildspec: codebuild/nodejs16.yml
       env:
         image: aws/codebuild/standard:5.0
-    - identifier: testBrowser18
-      buildspec: codebuild/browser18.yml
 
 # Integration Tests
-    - identifier: testVectorsNodejs20
-      buildspec: codebuild/test_vectors/nodejs20.yml
-      env:
-        variables:
-          PUBLISH_LOCAL: "true"
-        image: aws/codebuild/standard:5.0
-    - identifier: testVectorsBrowser18
-      buildspec: codebuild/test_vectors/browser18.yml
+    - identifier: testVectorsNodejs16
+      buildspec: codebuild/test_vectors/nodejs16.yml
       env:
         variables:
           PUBLISH_LOCAL: "true"
@@ -34,10 +26,8 @@ batch:
     - identifier: version
       depend-on:
         - compliance
-        - testNodejs20
-        - testBrowser18
-        - testVectorsNodejs20
-        - testVectorsBrowser18
+        - testNodejs16
+        - testVectorsNodejs16
       buildspec: codebuild/release/version.yml
       env:
         image: aws/codebuild/standard:6.0
@@ -54,15 +44,7 @@ batch:
     - identifier: validateNodejs
       depend-on:
         - publish
-      buildspec: codebuild/test_vectors/nodejs20.yml
-      env:
-        variables:
-          PUBLISH_LOCAL: "false"
-        image: aws/codebuild/standard:5.0
-    - identifier: validateBrowser
-      depend-on:
-        - publish
-      buildspec: codebuild/test_vectors/browser18.yml
+      buildspec: codebuild/test_vectors/nodejs16.yml
       env:
         variables:
           PUBLISH_LOCAL: "false"
diff --git a/codebuild/test_vectors/browser18.yml b/codebuild/test_vectors/browser18.yml
deleted file mode 100644
index 4ae2a8e97..000000000
--- a/codebuild/test_vectors/browser18.yml
+++ /dev/null
@@ -1,26 +0,0 @@
-version: 0.2
-
-env:
-  variables:
-    NODE_OPTIONS: "--max-old-space-size=4096"
-    NPM_CONFIG_UNSAFE_PERM: true
-
-phases:
-  install:
-    commands:
-      - n 18
-      - npm ci --unsafe-perm
-      - |-
-        if [ "$PUBLISH_LOCAL" = "true" ]; then
-          npm run build
-        fi
-  build:
-    commands:
-      - npm -v
-      - node -v
-      - |-
-        if [ "$PUBLISH_LOCAL" = "true" ]; then
-          npm run verdaccio-publish
-        fi
-      - npm run verdaccio-browser-decrypt
-      - npm run verdaccio-browser-encrypt
diff --git a/codebuild/test_vectors/nodejs18.yml b/codebuild/test_vectors/nodejs18.yml
deleted file mode 100644
index 982c2b1b7..000000000
--- a/codebuild/test_vectors/nodejs18.yml
+++ /dev/null
@@ -1,25 +0,0 @@
-version: 0.2
-
-env:
-  variables:
-    NODE_OPTIONS: "--max-old-space-size=4096"
-    NPM_CONFIG_UNSAFE_PERM: true
-
-phases:
-  install:
-    commands:
-      - n 18
-      - npm ci --unsafe-perm
-      - |-
-        if [ "$PUBLISH_LOCAL" = "true" ]; then
-          npm run build
-        fi
-  build:
-    commands:
-      - node -v
-      - |-
-        if [ "$PUBLISH_LOCAL" = "true" ]; then
-          npm run verdaccio-publish
-        fi
-      - npm run verdaccio-node-decrypt
-      - npm run verdaccio-node-encrypt
diff --git a/codebuild/test_vectors/nodejs20.yml b/codebuild/test_vectors/nodejs20.yml
deleted file mode 100644
index 3a2657beb..000000000
--- a/codebuild/test_vectors/nodejs20.yml
+++ /dev/null
@@ -1,25 +0,0 @@
-version: 0.2
-
-env:
-  variables:
-    NODE_OPTIONS: "--max-old-space-size=4096"
-    NPM_CONFIG_UNSAFE_PERM: true
-
-phases:
-  install:
-    commands:
-      - n 20
-      - npm ci --unsafe-perm
-      - |-
-        if [ "$PUBLISH_LOCAL" = "true" ]; then
-          npm run build
-        fi
-  build:
-    commands:
-      - node -v
-      - |-
-        if [ "$PUBLISH_LOCAL" = "true" ]; then
-          npm run verdaccio-publish
-        fi
-      - npm run verdaccio-node-decrypt
-      - npm run verdaccio-node-encrypt
diff --git a/modules/web-crypto-backend/package.json b/modules/web-crypto-backend/package.json
index 9bb91371a..38b70346f 100644
--- a/modules/web-crypto-backend/package.json
+++ b/modules/web-crypto-backend/package.json
@@ -19,7 +19,6 @@
   },
   "license": "Apache-2.0",
   "dependencies": {
-    "@aws-crypto/ie11-detection": "4.0.0",
     "@aws-crypto/supports-web-crypto": "5.2.0",
     "@aws-sdk/util-locate-window": "3.310.0",
     "tslib": "^2.2.0"
diff --git a/modules/web-crypto-backend/src/backend-factory.ts b/modules/web-crypto-backend/src/backend-factory.ts
index 289dd8a58..df843a86a 100644
--- a/modules/web-crypto-backend/src/backend-factory.ts
+++ b/modules/web-crypto-backend/src/backend-factory.ts
@@ -1,14 +1,12 @@
 // Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-import { isMsWindow } from '@aws-crypto/ie11-detection'
 import {
   supportsWebCrypto,
   supportsSubtleCrypto,
   supportsZeroByteGCM,
 } from '@aws-crypto/supports-web-crypto'
 import { generateSynchronousRandomValues } from './synchronous_random_values'
-import promisifyMsSubtleCrypto from './promisify-ms-crypto'
 
 type MaybeSubtleCrypto = SubtleCrypto | false
 export type WebCryptoBackend =
@@ -140,7 +138,6 @@ export function pluckSubtleCrypto(window: Window): MaybeSubtleCrypto {
   // if needed webkitSubtle check should be added here
   // see: https://webkit.org/blog/7790/update-on-web-cryptography/
   if (supportsWebCrypto(window)) return window.crypto.subtle
-  if (isMsWindow(window)) return promisifyMsSubtleCrypto(window.msCrypto.subtle)
   return false
 }
 
diff --git a/modules/web-crypto-backend/src/promisify-ms-crypto.ts b/modules/web-crypto-backend/src/promisify-ms-crypto.ts
deleted file mode 100644
index 4c17e629f..000000000
--- a/modules/web-crypto-backend/src/promisify-ms-crypto.ts
+++ /dev/null
@@ -1,38 +0,0 @@
-// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
-// SPDX-License-Identifier: Apache-2.0
-
-import { MsSubtleCrypto } from '@aws-crypto/ie11-detection'
-
-type MsSubtleFunctions = keyof MsSubtleCrypto
-
-export default function promisifyMsSubtleCrypto(backend: MsSubtleCrypto) {
-  const usages: MsSubtleFunctions[] = [
-    'decrypt',
-    'digest',
-    'encrypt',
-    'exportKey',
-    'generateKey',
-    'importKey',
-    'sign',
-    'verify',
-  ]
-  const decorateUsage = (fakeBackend: any, usage: MsSubtleFunctions) =>
-    decorate(backend, fakeBackend, usage)
-  return usages.reduce(decorateUsage, {}) as SubtleCrypto
-}
-
-function decorate(
-  subtle: MsSubtleCrypto,
-  fakeBackend: any,
-  name: MsSubtleFunctions
-) {
-  fakeBackend[name] = async (...args: any[]) => {
-    return new Promise((resolve, reject) => {
-      // @ts-ignore
-      const operation = subtle[name](...args)
-      operation.oncomplete = () => resolve(operation.result)
-      operation.onerror = reject
-    })
-  }
-  return fakeBackend
-}
diff --git a/modules/web-crypto-backend/src/synchronous_random_values.ts b/modules/web-crypto-backend/src/synchronous_random_values.ts
index 0a0147c06..86cfdba3e 100644
--- a/modules/web-crypto-backend/src/synchronous_random_values.ts
+++ b/modules/web-crypto-backend/src/synchronous_random_values.ts
@@ -1,7 +1,6 @@
 // Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-import { isMsWindow } from '@aws-crypto/ie11-detection'
 import { supportsSecureRandom } from '@aws-crypto/supports-web-crypto'
 import { locateWindow } from '@aws-sdk/util-locate-window'
 
@@ -19,10 +18,6 @@ export function generateSynchronousRandomValues(
   return function synchronousRandomValues(byteLength: number): Uint8Array {
     if (supportsSecureRandom(globalScope)) {
       return globalScope.crypto.getRandomValues(new Uint8Array(byteLength))
-    } else if (isMsWindow(globalScope)) {
-      const values = new Uint8Array(byteLength)
-      globalScope.msCrypto.getRandomValues(values)
-      return values
     }
 
     throw new Error(`Unable to locate a secure random source.`)
diff --git a/modules/web-crypto-backend/test/fixtures.ts b/modules/web-crypto-backend/test/fixtures.ts
index edddc884f..cc51f9fea 100644
--- a/modules/web-crypto-backend/test/fixtures.ts
+++ b/modules/web-crypto-backend/test/fixtures.ts
@@ -3,7 +3,12 @@
 
 export const fakeWindowWebCryptoSupportsZeroByteGCM: Window = {
   crypto: {
-    getRandomValues: () => {},
+    getRandomValues: (array: Uint8Array) => {
+      for (let i = 0; i < array.length; i++) {
+        array[i] = Math.floor(Math.random() * 256)
+      }
+      return array
+    },
     subtle: {
       async decrypt() {
         return {} as any
@@ -142,145 +147,3 @@ export const subtleFallbackZeroByteEncryptFail = {
 } as any
 
 export const subtleFallbackNoWebCrypto = {} as any
-
-export const fakeWindowIE11OnComplete = {
-  msCrypto: {
-    getRandomValues: (values: Uint8Array) => {
-      return values.fill(1)
-    },
-    subtle: {
-      decrypt() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.result = true
-          obj.oncomplete()
-        })
-        return obj
-      },
-      digest() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.result = true
-          obj.oncomplete()
-        })
-        return obj
-      },
-      encrypt() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.result = true
-          obj.oncomplete()
-        })
-        return obj
-      },
-      exportKey() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.result = true
-          obj.oncomplete()
-        })
-        return obj
-      },
-      generateKey() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.result = true
-          obj.oncomplete()
-        })
-        return obj
-      },
-      importKey() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.result = true
-          obj.oncomplete()
-        })
-        return obj
-      },
-      sign() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.result = true
-          obj.oncomplete()
-        })
-        return obj
-      },
-      verify() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.result = true
-          obj.oncomplete()
-        })
-        return obj
-      },
-    },
-  },
-  MSInputMethodContext: {} as any,
-} as any
-
-export const fakeWindowIE11OnError = {
-  msCrypto: {
-    getRandomValues: (values: Uint8Array) => {
-      return values.fill(1)
-    },
-    subtle: {
-      decrypt() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.onerror(new Error('stub error'))
-        })
-        return obj
-      },
-      digest() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.onerror(new Error('stub error'))
-        })
-        return obj
-      },
-      encrypt() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.onerror(new Error('stub error'))
-        })
-        return obj
-      },
-      exportKey() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.onerror(new Error('stub error'))
-        })
-        return obj
-      },
-      generateKey() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.onerror(new Error('stub error'))
-        })
-        return obj
-      },
-      importKey() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.onerror(new Error('stub error'))
-        })
-        return obj
-      },
-      sign() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.onerror(new Error('stub error'))
-        })
-        return obj
-      },
-      verify() {
-        const obj = {} as any
-        setTimeout(() => {
-          obj.onerror(new Error('stub error'))
-        })
-        return obj
-      },
-    },
-  },
-  MSInputMethodContext: {} as any,
-} as any
diff --git a/modules/web-crypto-backend/test/promisify-ms-crypto.test.ts b/modules/web-crypto-backend/test/promisify-ms-crypto.test.ts
deleted file mode 100644
index 7c420478f..000000000
--- a/modules/web-crypto-backend/test/promisify-ms-crypto.test.ts
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
-// SPDX-License-Identifier: Apache-2.0
-
-/* eslint-env mocha */
-
-import * as chai from 'chai'
-import chaiAsPromised from 'chai-as-promised'
-import promisifyMsSubtleCrypto from '../src/promisify-ms-crypto'
-import * as fixtures from './fixtures'
-
-chai.use(chaiAsPromised)
-const { expect } = chai
-
-/* These tests are very simple
- * I am not testing every subtle function
- * because the promisify code is all the same.
- */
-describe('promisifyMsSubtleCrypto', () => {
-  const backendComplete = promisifyMsSubtleCrypto(
-    fixtures.fakeWindowIE11OnComplete.msCrypto.subtle
-  )
-  const backendError = promisifyMsSubtleCrypto(
-    fixtures.fakeWindowIE11OnError.msCrypto.subtle
-  )
-
-  it('backendComplete:decrypt', async () => {
-    // @ts-ignore These methods are stubs, ignore ts errors
-    const test = await backendComplete.decrypt()
-    expect(test).to.equal(true)
-  })
-
-  it('backendError:decrypt', async () => {
-    // @ts-ignore These methods are stubs, ignore ts errors
-    await expect(backendError.decrypt()).to.rejectedWith(Error)
-  })
-})
diff --git a/modules/web-crypto-backend/test/synchronous_random_values.test.ts b/modules/web-crypto-backend/test/synchronous_random_values.test.ts
index 1c8d52456..8e3a06bf9 100644
--- a/modules/web-crypto-backend/test/synchronous_random_values.test.ts
+++ b/modules/web-crypto-backend/test/synchronous_random_values.test.ts
@@ -5,25 +5,15 @@
 
 import { expect } from 'chai'
 import { generateSynchronousRandomValues } from '../src/synchronous_random_values'
-import { synchronousRandomValues } from '../src/index'
 import * as fixtures from './fixtures'
 
 describe('synchronousRandomValues', () => {
   it('should return random values', () => {
-    const test = synchronousRandomValues(5)
-    expect(test).to.be.instanceOf(Uint8Array)
-    expect(test).lengthOf(5)
-  })
-
-  it('should return msCrypto random values', () => {
     const synchronousRandomValues = generateSynchronousRandomValues(
-      fixtures.fakeWindowIE11OnComplete
+      fixtures.fakeWindowWebCryptoSupportsZeroByteGCM
     )
-
     const test = synchronousRandomValues(5)
     expect(test).to.be.instanceOf(Uint8Array)
     expect(test).lengthOf(5)
-    // The random is a stub, so I know the value
-    expect(test).to.deep.equal(new Uint8Array(5).fill(1))
   })
 })
diff --git a/package-lock.json b/package-lock.json
index 16310b417..e5bea0bb0 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -711,23 +711,11 @@
       "version": "4.0.1",
       "license": "Apache-2.0",
       "dependencies": {
-        "@aws-crypto/ie11-detection": "4.0.0",
         "@aws-crypto/supports-web-crypto": "5.2.0",
         "@aws-sdk/util-locate-window": "3.310.0",
         "tslib": "^2.2.0"
       }
     },
-    "modules/web-crypto-backend/node_modules/@aws-crypto/ie11-detection": {
-      "version": "4.0.0",
-      "license": "Apache-2.0",
-      "dependencies": {
-        "tslib": "^1.11.1"
-      }
-    },
-    "modules/web-crypto-backend/node_modules/@aws-crypto/ie11-detection/node_modules/tslib": {
-      "version": "1.14.1",
-      "license": "0BSD"
-    },
     "modules/web-crypto-backend/node_modules/@aws-sdk/util-locate-window": {
       "version": "3.310.0",
       "license": "Apache-2.0",