Apple reinforces iMessage security with contact key verification

AppleInsiderAppleInsider
Posted:
in iOS

Apple enhances iMessage security with "Contact Key Verification," fortifying user privacy and identity verification against evolving threats using cryptographic methods and Key Transparency.

An example of an alert from iMessage Contact Key Verification
An example of an alert from iMessage Contact Key Verification



Contact Key Verification is a security feature that helps detect sophisticated attacks on iMessage servers and allows users to verify the identity of their communication partners. This feature specifically addresses the vulnerabilities that are associated with key directory services.

Such services usually map user identifiers to public keys, which could become a single point of failure if they get compromised. Contact Key Verification aims to overcome this issue by providing a more secure way of verifying the identities of communication partners.

To tackle this issue, Apple has introduced a mechanism known as Key Transparency (KT). Similar to Certificate Transparency, KT uses a verifiable log-backed map data structure that allows cryptographic proofs and audits for consistency over time, offering scalability and user privacy. Apple's implementation of Key Transparency goes beyond the existing key directory system.

It introduces an account-level ECDSA signing key, generated and stored on the user's device in iCloud Keychain. Devices use this synchronized account key to sign iMessage public keys, and this data is stored in the Identity Directory Service (IDS) database and synchronized with the Key Transparency service.

When users enable Contact Key Verification, their devices automatically and cryptographically verify the data presented by IDS against the KT map. If inconsistencies are detected, users are notified. Furthermore, users' own devices periodically verify the data to ensure consistency across all their devices.




Apple has also incorporated a feature for manual contact verification using shortcodes, providing an additional layer of security for users who require it. This verification process extends to all users' devices, maintaining consistency when signing in on new devices.

In addition, Apple has introduced public verification codes for users with public personas, ensuring that their contact key is accurately verified.

Apple's implementation includes on-device verification of critical append-only logs for user control and security. The Messages app verifies log consistency, addressing potential compromise of the KT service.

Apple will launch Key Transparency, with internal auditing across production trees and more details to follow about public auditing. iMessage Contact Key Verification is available in developer previews of iOS 17.2, macOS 14.2, and watchOS 10.2, promising enhanced security for Apple's messaging platform.

Read on AppleInsider

Comments

  • Reply 1 of 12
    appleinsideruserappleinsideruser Posts: 495member
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
  • Reply 2 of 12
    chasmchasm Posts: 3,306member
    appleinsideruser said:
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
    No, they’re not saying that. Sorry you didn’t understand the article.
    watto_cobra
  • Reply 3 of 12
    appleinsideruserappleinsideruser Posts: 495member
    chasm said:
    appleinsideruser said:
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
    No, they’re not saying that. Sorry you didn’t understand the article.
    The article had lots of clear, understandable, specific details. However, it seemed to not address the bigger picture of why this complexity is needed.
    gatorguy
  • Reply 4 of 12
    Fidonet127Fidonet127 Posts: 508member
    I'm running 17.2 and see no option in settings for messages for this.
    watto_cobra
  • Reply 5 of 12
    lowededwookielowededwookie Posts: 1,143member
    appleinsideruser said:
    chasm said:
    appleinsideruser said:
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
    No, they’re not saying that. Sorry you didn’t understand the article.
    The article had lots of clear, understandable, specific details. However, it seemed to not address the bigger picture of why this complexity is needed.
    An ounce of prevention is worth more than a pound of cure.

    In other words, the reason for this complexity is to prevent scumbags stealing our data. Does Apple really need to have more of a reason to implement better security?
    muthuk_vanalingamappleinsideruser
  • Reply 6 of 12
    appleinsideruserappleinsideruser Posts: 495member
    lowededwookie said:
    appleinsideruser said:
    chasm said:
    appleinsideruser said:
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
    No, they’re not saying that. Sorry you didn’t understandj the article.
    The article had lots of clear, understandable, specific details. However, it seemed to not address the bigger picture of why this complexity is needed.
    An ounce of prevention is worth more than a pound of cure.

    In other words, the reason for this complexity is to prevent scumbags stealing our data. Does Apple really need to have more of a reason to implement better security?
    Yes indeed. So I just wondered why not hide the complexity (as they usually do) by fixing the underlying vulnerability, prevent the attack, and spare us this odd carbuncle? What is the attack vector they are addressing?
  • Reply 7 of 12
    HonkersHonkers Posts: 156member
    chasm said:
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
    No, they’re not saying that. Sorry you didn’t understandj the article.
    The article had lots of clear, understandable, specific details. However, it seemed to not address the bigger picture of why this complexity is needed.
    An ounce of prevention is worth more than a pound of cure.

    In other words, the reason for this complexity is to prevent scumbags stealing our data. Does Apple really need to have more of a reason to implement better security?
    Yes indeed. So I just wondered why not hide the complexity (as they usually do) by fixing the underlying vulnerability, prevent the attack, and spare us this odd carbuncle? What is the attack vector they are addressing?
    "for users who require it"

    You don't require it.  Calm down.
    williamlondon
  • Reply 8 of 12
    gatorguygatorguy Posts: 24,213member
    chasm said:
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
    No, they’re not saying that. Sorry you didn’t understandj the article.
    The article had lots of clear, understandable, specific details. However, it seemed to not address the bigger picture of why this complexity is needed.
    An ounce of prevention is worth more than a pound of cure.

    In other words, the reason for this complexity is to prevent scumbags stealing our data. Does Apple really need to have more of a reason to implement better security?
    Yes indeed. So I just wondered why not hide the complexity (as they usually do) by fixing the underlying vulnerability, prevent the attack, and spare us this odd carbuncle? What is the attack vector they are addressing?
    Look for articles regarding "man-in-the-middle" exploits, undisclosed listeners sometimes referred to as "ghost participants" in an encrypted conversation. Yes, Apple's iMessage is vulnerable and has been since it became a feature, but unless you're on the radar of a state agency I don't think any of us need worry. Of note, the UK's spy agency somewhat recently suggested that cooperation become law. 

    EDIT: Here's one old article that explains it.
    https://threatpost.com/apple-imessage-open-to-man-in-the-middle-spoofing-attacks/102610/
    edited October 2023 appleinsiderusermuthuk_vanalingamctt_zhFileMakerFellerjony0
  • Reply 9 of 12
    appleinsideruserappleinsideruser Posts: 495member
    gatorguy said:
    chasm said:
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
    No, they’re not saying that. Sorry you didn’t understandj the article.
    The article had lots of clear, understandable, specific details. However, it seemed to not address the bigger picture of why this complexity is needed.
    An ounce of prevention is worth more than a pound of cure.

    In other words, the reason for this complexity is to prevent scumbags stealing our data. Does Apple really need to have more of a reason to implement better security?
    Yes indeed. So I just wondered why not hide the complexity (as they usually do) by fixing the underlying vulnerability, prevent the attack, and spare us this odd carbuncle? What is the attack vector they are addressing?
    Look for articles regarding "man-in-the-middle" exploits, undisclosed listeners sometimes referred to as "ghost participants" in an encrypted conversation. Yes, Apple's iMessage is vulnerable and has been since it became a feature, but unless you're on the radar of a state agency I don't think any of us need worry. Of note, the UK's spy agency somewhat recently suggested it become law. 

    EDIT: Here's one old article that explains it.
    https://threatpost.com/apple-imessage-open-to-man-in-the-middle-spoofing-attacks/102610/
    Thanks for the reference. It seems the Threat Post people suggest that iMessage could use certificate pinning to avoid the MITM attack. I guess that’s the sort of fix I was expecting.

    Seems neater and with no need for the 2nd channel verification carbuncle (and any lack of calmness). 
  • Reply 10 of 12
    gatorguygatorguy Posts: 24,213member
    gatorguy said:
    chasm said:
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
    No, they’re not saying that. Sorry you didn’t understandj the article.
    The article had lots of clear, understandable, specific details. However, it seemed to not address the bigger picture of why this complexity is needed.
    An ounce of prevention is worth more than a pound of cure.

    In other words, the reason for this complexity is to prevent scumbags stealing our data. Does Apple really need to have more of a reason to implement better security?
    Yes indeed. So I just wondered why not hide the complexity (as they usually do) by fixing the underlying vulnerability, prevent the attack, and spare us this odd carbuncle? What is the attack vector they are addressing?
    Look for articles regarding "man-in-the-middle" exploits, undisclosed listeners sometimes referred to as "ghost participants" in an encrypted conversation. Yes, Apple's iMessage is vulnerable and has been since it became a feature, but unless you're on the radar of a state agency I don't think any of us need worry. Of note, the UK's spy agency somewhat recently suggested it become law. 

    EDIT: Here's one old article that explains it.
    https://threatpost.com/apple-imessage-open-to-man-in-the-middle-spoofing-attacks/102610/
    Thanks for the reference. It seems the Threat Post people suggest that iMessage could use certificate pinning to avoid the MITM attack. I guess that’s the sort of fix I was expecting.

    Seems neater and with no need for the 2nd channel verification carbuncle (and any lack of calmness). 
    Of note, Apple controls the naming of devices in the directory mapping account. There's no outside way of proving that all of the listed devices connected to you factually belong to your account or to the account they claim to be part of.  Therefor, your iDevice simply trusts whatever Apple says, not that it is actually true all the devices in a conversation belong to who you believe they do. 
    ctt_zhappleinsideruserFileMakerFeller
  • Reply 11 of 12
    coolfactorcoolfactor Posts: 2,245member
    chasm said:
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
    No, they’re not saying that. Sorry you didn’t understand the article.
    The article had lots of clear, understandable, specific details. However, it seemed to not address the bigger picture of why this complexity is needed.

    User: "Hey Apple, please make sure our iOS and macOS devices are rock-solid secure."
    Apple: "We are always looking for ways to increase security in these fast-paced times, with new threats emerging all the time."
    User: "Great! This is why I buy your products."
    Apple: "We've introduced a new contact keys feature that will make messaging more secure."
    User: "Great, but why all the complexity?"

     :( 
    edited October 2023 beowulfschmidt
  • Reply 12 of 12
    appleinsideruserappleinsideruser Posts: 495member
    coolfactor said:
    chasm said:
    So is this saying that iCloud is flawed and 3rd parties can secretly add a snooping iMessage device to the account? If so, why not fix this flaw, rather than reporting when it’s happened?
    No, they’re not saying that. Sorry you didn’t understand the article.
    The article had lots of clear, understandable, specific details. However, it seemed to not address the bigger picture of why this complexity is needed.

    User: "Hey Apple, please make sure our iOS and macOS devices are rock-solid secure."
    Apple: "We are always looking for ways to increase security in these fast-paced times, with new threats emerging all the time."
    User: "Great! This is why I buy your products."
    Apple: "We've introduced a new contact keys feature that will make messaging more secure."
    User: "Great, but why all the complexity?"

     :( 
    Sadly, looks like the last Apple: reply got lost 😂
    FileMakerFeller
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